Allied Command Operations
Allied Command Operations (ACO) is one of the North Atlantic Treaty Organization's (NATO) two strategic military commands, tasked with preparing for, planning, conducting, and executing all NATO-led military operations, missions, and tasks to fulfill the Alliance's strategic objectives.[1] Headquartered at Supreme Headquarters Allied Powers Europe (SHAPE) in Mons, Belgium, ACO maintains a three-tier command structure spanning strategic, operational, and tactical levels to ensure effective oversight of NATO forces.[2] Led by the Supreme Allied Commander Europe (SACEUR), who doubles as one of NATO's principal military authorities and is traditionally a United States officer, ACO focuses on enhancing Alliance readiness for deterrence, collective defence, and crisis response.[3] Its operational components include Joint Force Commands such as those in Brunssum, Naples, and Norfolk, which handle theatre-level planning and execution across land, maritime, air, and joint domains.[2] Through these elements, ACO has underpinned NATO's military engagements, from post-Cold War peacekeeping in the Balkans to contemporary enhancements in forward presence amid evolving security challenges, prioritizing empirical force generation and interoperability among member states.[1]History
Origins in Cold War NATO Command Structures
The establishment of Allied Command Operations (ACO) traces its roots to NATO's early Cold War military command architecture, designed to counter the Soviet threat through collective defense. Following the North Atlantic Treaty of April 4, 1949, NATO initially operated without a centralized military headquarters, relying on national contributions. The Korean War's outbreak on June 25, 1950, accelerated the need for integrated command, leading to the appointment of General Dwight D. Eisenhower as the first Supreme Allied Commander Europe (SACEUR) on December 19, 1950.[4] This role centralized operational authority over allied forces in Europe, emphasizing deterrence against potential Warsaw Pact aggression. On April 2, 1951, Supreme Headquarters Allied Powers Europe (SHAPE) was activated at Rocquencourt, France, as the headquarters for Allied Command Europe (ACE), the direct precursor to ACO. SHAPE served as the nerve center for coordinating multinational land, sea, and air forces across NATO's European theater, with SACEUR exercising operational command under the North Atlantic Council and Military Committee. The structure prioritized forward defense along the inner-German border, integrating forces from 12 initial member nations into a unified framework governed by Article 5's mutual defense clause. By 1952, expansions included Greece and Turkey, enhancing southern flank coverage.[5][6] ACE's command hierarchy during the Cold War featured two strategic-level commands—ACE for continental operations and Allied Command Atlantic (ACLANT) for maritime approaches—underpinning NATO's overall posture. Subordinate major commands emerged, such as Allied Forces Central Europe (AFCENT) in 1953, Allied Forces Northern Europe (AFNORTH) in 1954, and Allied Forces Southern Europe (AFSOUTH), dividing responsibilities geographically to address the Soviet bloc's numerical superiority through alliance cohesion and rapid mobilization. This setup, peaking at 78 headquarters, focused on massive reinforcement from North America and in-place defenses, with exercises like REFORGER testing interoperability. France's 1966 withdrawal from the integrated command prompted SHAPE's relocation to Casteau, Belgium, in 1967, while maintaining dual U.S.-European leadership for SACEUR to ensure transatlantic commitment.[1] These Cold War foundations emphasized static deterrence and conventional warfighting doctrines, such as "Halt Phase" strategies to hold ground until reinforcements arrived, reflecting causal assessments of Soviet blitzkrieg tactics. ACE's evolution under successive SACEURs, always dual-hatted U.S. European Command leaders, institutionalized NATO's operational readiness, providing the structural template later streamlined into ACO amid post-1991 shifts.[7]Post-Cold War Reorganization (1990s-2000s)
Following the dissolution of the Warsaw Pact in 1991 and the adoption of NATO's new Strategic Concept at the Rome Summit on November 7-8, 1991, the Alliance initiated a comprehensive review of its military command structure to adapt to a post-Cold War environment characterized by reduced conventional threats and emerging requirements for crisis management and peacekeeping operations.[1] This Long-Term Study, launched in response to the 1990 London Declaration, emphasized flexibility, leading to the introduction of the Combined Joint Task Force (CJTF) concept approved by NATO defense ministers in December 1993, which enabled the creation of ad hoc, multinational forces for rapid deployment without permanent headquarters.[1] By the mid-1990s, initial force reductions had streamlined Allied Command Europe (ACE), the predecessor to ACO, from a Cold War-era network of over 70 major subordinate commands focused on static defense against Soviet invasion to a more agile structure supporting operations like the Implementation Force (IFOR) in Bosnia-Herzegovina in 1995.[1] In the late 1990s, further adaptations addressed operational experiences in the Balkans, including the 1999 Kosovo air campaign, prompting incremental command efficiencies such as the consolidation of regional commands and enhanced interoperability for out-of-area missions.[1] These changes reduced the overall NATO command headquarters from 78 during the Cold War to approximately 32 by 2000, prioritizing deployable elements over fixed infrastructure while maintaining SHAPE as the central hub under the Supreme Allied Commander Europe (SACEUR).[1] The pivotal reorganization occurred at the Prague Summit on November 21-22, 2002, where NATO leaders approved a fundamental restructuring to create a leaner, expeditionary-focused command system capable of addressing asymmetric threats and global contingencies.[8] This reform divided NATO's strategic commands into two: Allied Command Operations (ACO) for planning and executing all joint, multinational operations, headquartered at SHAPE in Mons, Belgium, and Allied Command Transformation (ACT) for capability development; ACE was formally redesignated ACO on July 29, 2003, with the number of operational-level commands reduced from 32 to just nine, including three Joint Force Commands, to enhance agility and reduce redundancies.[1][8] The changes emphasized transatlantic balance, with ACO retaining responsibility for collective defense under Article 5 while enabling rapid response forces, marking a shift from territorial defense to a hybrid model integrating peacetime vigilance with crisis projection.[8]Adaptations to 21st-Century Threats
Following Russia's annexation of Crimea in 2014, Allied Command Operations (ACO) implemented the Readiness Action Plan (RAP) at the NATO Wales Summit, comprising immediate assurance measures—such as enhanced air policing with fighter jets stationed in Estonia, Latvia, and Lithuania from May 2014—and longer-term adaptations to NATO's forces and command structure to bolster deterrence and defense capabilities.[9] These adaptations tripled the NATO Response Force (NRF) to approximately 40,000 personnel and established the Very High Readiness Joint Task Force (VJTF), a spearhead component of about 5,000 ground forces deployable within 2-3 days.[9] By 2016, at the Warsaw Summit, RAP evolved into baseline enhancements, including the Enhanced Forward Presence (eFP) with multinational battlegroups in the Baltic states, Poland, and later Romania and Bulgaria, directly under ACO oversight to counter territorial threats from the east.[9][1] ACO underwent structural reforms to support rapid reinforcement and sustainment in high-intensity scenarios, notably the creation of the Joint Support and Enabling Command (JSEC) in Ulm, Germany, in 2018, which facilitates swift troop movements across Europe as the "SACEUR's Rear Area" and achieved Full Operational Capability in September 2021.[1][10] Concurrently, Joint Force Command Norfolk was established in the United States in 2018 to safeguard transatlantic lines of communication amid renewed focus on Article 5 collective defense.[1] These changes addressed logistical bottlenecks exposed by hybrid and conventional threats, enabling ACO to coordinate eight NATO Force Integration Units (NFIUs) in Central and Eastern Europe by 2017 for seamless force flow.[9] To counter 21st-century domains like cyberspace and space, ACO integrated these into operations: the Cyberspace Operations Centre opened in Belgium following the 2018 Brussels Summit for enhanced situational awareness against destructive cyber threats, which NATO recognized as an operational domain in 2016.[1] In October 2020, the NATO Space Centre at Ramstein Air Base, Germany, was activated to mitigate threats to satellites and support multi-domain coordination.[1] These adaptations respond to hybrid warfare tactics, including Russian-attributed cyber intrusions and information operations, by embedding resilience into ACO's planning for integrated deterrence across air, land, sea, cyber, and space.[11][1] Post-2022 Russian invasion of Ukraine, ACO further scaled eFP with four additional battlegroups and advanced the NATO Force Model for scalable, high-readiness forces.[9]Mission and Responsibilities
Core Strategic Objectives
Allied Command Operations (ACO) functions as NATO's principal warfighting command, tasked with preparing for, planning, conducting, and executing military operations to fulfill the Alliance's political objectives. Its core strategic objectives align with NATO's three foundational tasks outlined in the 2022 Strategic Concept: deterrence and defense against aggression; crisis prevention and management to address emerging threats; and cooperative security to build partnerships that enhance stability. Through these, ACO seeks to deter potential adversaries, protect Alliance territory, and ensure a credible response to armed attacks or hybrid threats.[1][12][13] A primary objective is to maintain the territorial integrity of NATO member states by safeguarding sea lanes, economic lifelines, and airspace, thereby preserving freedom of action for Allied forces and populations. This involves strategic-level oversight from Supreme Headquarters Allied Powers Europe (SHAPE) to integrate multinational forces for rapid deployment and sustained operations, emphasizing collective defense under Article 5 of the North Atlantic Treaty. ACO also prioritizes enhancing deterrence through visible readiness, such as reinforced forward presence in Eastern Europe since 2017, to counter revisionist powers like Russia.[1][14][15] In crisis management, ACO's objectives extend to non-Article 5 missions, including stabilization, counter-terrorism, and humanitarian support, as demonstrated in past operations like those in the Balkans and Afghanistan. These efforts aim to prevent escalation, manage conflicts short of full-scale war, and support post-conflict reconstruction while coordinating with civilian agencies. Cooperative security objectives involve fostering interoperability with non-NATO partners through exercises and joint planning, ensuring ACO can execute missions that bolster global security without overextending Alliance resources.[1][12][16]Role in NATO's Operational Framework
Allied Command Operations (ACO) serves as one of NATO's two strategic-level commands within the Alliance's military command structure, responsible for the planning, preparation, conduct, and execution of all NATO military operations, missions, and tasks to achieve strategic objectives defined by the North Atlantic Council (NAC) and the Military Committee.[1] Headquartered at Supreme Headquarters Allied Powers Europe (SHAPE) in Mons, Belgium, ACO operates under the dual-hatted command of the Supreme Allied Commander Europe (SACEUR), who is concurrently the Commander of United States European Command, ensuring integration of NATO efforts with U.S. military priorities.[2] This structure positions ACO at the apex of operational command, bridging political directives from the NAC—NATO's principal political decision-making body—with tactical execution through subordinate joint force commands and component commands.[17] In NATO's operational framework, ACO maintains a three-tier hierarchy encompassing strategic, operational, and tactical levels, enabling scalable responses to crises ranging from collective defense under Article 5 of the North Atlantic Treaty to crisis management and cooperative security operations.[2] It coordinates with Allied Command Transformation (ACT) to incorporate doctrinal innovations, training, and capability development into operational planning, while ensuring interoperability among the 32 member states' forces through standardized procedures and exercises.[14] ACO's role emphasizes readiness for high-intensity peer conflicts, as evidenced by its adaptation post-2014 to enhanced forward presence in Eastern Europe, involving multinational battlegroups in Estonia, Latvia, Lithuania, and Poland, each comprising approximately 1,000-1,500 troops from framework nations and allies.[1] This framework underscores ACO's mandate to deter aggression, particularly from Russia, by maintaining credible combat power deployable within days, as demonstrated in exercises like Steadfast Defender 2024, which mobilized over 90,000 personnel across Europe.[18] ACO's operational primacy is delineated from political oversight, with the NAC approving missions only after consensus among Allies, after which ACO assumes command responsibility, allowing individual nations to opt into contributions based on national caveats.[19] This delineation preserves Alliance unity while accommodating varying member commitments, as seen in operations like Enhanced Air Policing, which since 2014 has conducted over 500 intercepts to enforce Baltic airspace integrity without territorial incursions.[1] Through its Joint Operations Planning Group and crisis management processes, ACO integrates intelligence from the Joint Intelligence and Security Division, ensuring operations align with the Alliance's 2022 Strategic Concept prioritizing deterrence and defense amid hybrid threats and great-power competition.[2]Coordination with Allied Command Transformation
Allied Command Operations (ACO) and Allied Command Transformation (ACT) constitute NATO's two strategic military commands, established following the 2002 Prague Summit to streamline the Alliance's command structure. ACO, headquartered at Supreme Headquarters Allied Powers Europe (SHAPE) in Mons, Belgium, focuses on planning, conducting, and executing military operations, while ACT, based in Norfolk, Virginia, drives the continuous transformation of NATO's forces, capabilities, and doctrines to address evolving security challenges. This division ensures that operational execution benefits from ongoing adaptation and innovation.[1][17] Coordination between ACO and ACT occurs through integrated mechanisms within the NATO Command Structure, including ACT's maintenance of a dedicated staff element at SHAPE to facilitate direct liaison and support. ACT enables ACO by providing pre-deployment training, analyzing lessons learned from operations, and augmenting capabilities during crises, thereby bridging current missions with future requirements. Both commands jointly advise the NATO Military Committee on strategic military matters, particularly through the NATO Defence Planning Process, which aligns national contributions with Alliance needs.[17][14] Key areas of collaboration include the development and management of common-funded capability programs, overseen by ACT in coordination with ACO under the Common Funded Capability Delivery Governance Model to enhance multi-domain operations. ACT leads the formulation of doctrines, such as those for cyberspace operations, and supports interoperability via initiatives like the Coalition Warrior Interoperability eXercise (CWIX). Since July 2012, ACT has managed collective training and exercises tailored to ACO's operational demands, with both commands partnering on major events like Steadfast Defender to test readiness and integrate transformative concepts.[14][20][21]Organizational Structure
Supreme Headquarters Allied Powers Europe (SHAPE)
Supreme Headquarters Allied Powers Europe (SHAPE) serves as the strategic military headquarters for NATO's Allied Command Operations (ACO), directing the planning, direction, and coordination of all Alliance military activities and operations. Situated in Casteau, Belgium, approximately 15 kilometers south of Mons, SHAPE functions as the central hub for NATO's collective defense in the Euro-Atlantic area, exercising command over forces from 32 member nations.[22][13] SHAPE was formally established on 2 April 1951, two years after the signing of the North Atlantic Treaty in 1949, to integrate NATO's military efforts amid rising Cold War tensions following the Korean War. Initially headquartered at Fontainebleau, France, under the command of General Dwight D. Eisenhower as the first Supreme Allied Commander Europe (SACEUR), it oversaw Allied Command Europe (ACE) with a focus on deterring Soviet aggression through forward-deployed forces. In response to France's 1966 decision to withdraw from NATO's integrated military command, SHAPE relocated to its current Belgian site on 1 April 1967, enhancing operational continuity and Alliance cohesion. Post-Cold War, the 2002 Prague Summit reforms transformed ACE into ACO in 2003, broadening SHAPE's remit to include expeditionary operations beyond Europe while maintaining deterrence as its core function.[5][23] The commander of SHAPE is the SACEUR, a position held exclusively by a United States four-star general or flag officer who is dual-hatted as Commander of United States European Command (USEUCOM), ensuring seamless integration of U.S. and NATO strategic priorities. General Alexus G. Grynkewich, United States Air Force, assumed the role on 4 July 2025, succeeding General Christopher G. Cavoli. Supporting the SACEUR is the Deputy Supreme Allied Commander Europe (DSACEUR), typically a senior officer from a European NATO ally, along with a Chief of Staff and Vice Chief of Staff who manage daily operations and staff divisions focused on strategy, operations, logistics, and intelligence.[3][24] SHAPE's organizational structure aligns with NATO's tiered command framework: at the strategic level, it issues high-level directives; operationally, it supervises three Joint Force Commands—Brunssum (Netherlands), Naples (Italy), and Norfolk (United States)—responsible for theater-specific execution; and tactically, it liaises with component commands such as Allied Air Command in Ramstein, Germany, for domain-specific capabilities. This setup, refined through post-2014 adaptations to hybrid threats from Russia and others, emphasizes rapid response, interoperability, and sustainment of high-readiness forces like the NATO Response Force, with over 300 personnel at SHAPE ensuring 24/7 operational readiness.[2][18]Operational-Level Joint Force Commands
The operational level of Allied Command Operations (ACO) comprises three standing Joint Force Commands (JFCs): Joint Force Command Brunssum in the Netherlands, Joint Force Command Naples in Italy, and Joint Force Command Norfolk in the United States. These commands serve as the primary operational headquarters capable of planning, generating, deploying, sustaining, and redeploying multinational joint forces for NATO missions, including deterrence, crisis management, and collective defense. Each JFC maintains a high readiness posture to assume command of assigned forces, with scalability to lead major joint operations as directed by the Supreme Allied Commander Europe (SACEUR).[1][2] Joint Force Command Brunssum (JFC Brunssum), headquartered in Brunssum, Netherlands, focuses on operations oriented toward NATO's eastern flank and broader European theater. Established as a core component of ACO's post-2010 reforms, it builds on legacy infrastructure from the former Allied Forces Central Europe command dating to 1967 and is dual-hatted with the Rapid Deployable Corps Netherlands for enhanced deployability. JFC Brunssum's responsibilities include exercising regional defense plans, particularly in scenarios involving high-intensity conflict, and it supports ongoing missions through force generation and interoperability training. As of 2024, it contributes to NATO's forward posture enhancements amid heightened tensions with Russia.[25][26][27] Joint Force Command Naples (JFC Naples), located in Lago Patria near Naples, Italy, specializes in operations across the Mediterranean, Africa, and the Middle East, with an emphasis on southern flank security challenges such as migration, terrorism, and instability. It leads or supports missions including the NATO Mission Iraq (NMI), Kosovo Force (KFOR), and Headquarters Multinational Division Southeast Europe in Sarajevo. Capable of commanding up to a major joint operation, JFC Naples integrates air, land, maritime, and special operations components, drawing on subordinate elements like Maritime Command (MARCOM) for sea control. Its structure enables rapid response to hybrid threats and partnerships with non-NATO actors in the region.[28][25][2] Joint Force Command Norfolk (JFC Norfolk), based in Norfolk, Virginia, United States, addresses transatlantic reinforcement, maritime security in the North Atlantic, and Arctic domain awareness, reinforcing NATO's northern flank against potential disruptions to sea lines of communication. Activated in 2018 and achieving Full Operational Capability on July 15, 2021, it leverages U.S. military infrastructure while remaining fully multinational, with a focus on high-end warfighting and logistics sustainment for transatlantic operations. JFC Norfolk supports NATO's defense planning through exercises simulating large-scale reinforcements from North America and collaborates closely with Allied Command Transformation for capability development.[29][30][31] These JFCs operate in a networked fashion, with command and control enabled by ACO's strategic headquarters at SHAPE, ensuring synchronized responses across theaters without fixed geographic boundaries. They are scalable, with headquarters that can deploy forward if required, and emphasize jointness through integration of multinational staffs averaging 200-300 personnel each.[2][32]Joint Support and Enabling Command (JSEC)
The Joint Support and Enabling Command (JSEC) is a static operational-level headquarters of NATO's Allied Command Operations, located in Ulm, Germany, and subordinate to Supreme Headquarters Allied Powers Europe (SHAPE) in Mons, Belgium.[33] Established in 2018 as part of NATO's response to Russian aggression in Ukraine, JSEC was designed to enhance the Alliance's ability to coordinate the deployment, reinforcement, and sustainment of forces across Europe.[31] It declared full operational capability on September 8, 2021, becoming the second command to achieve this status that year.[10] In January 2025, JSEC transitioned from NATO's Force Structure to the permanent Command Structure, reflecting its expanded institutional role.[33] JSEC's primary mission is to enable and sustain NATO forces by coordinating reinforcement and sustainment activities during crises or conflicts, while advising the Supreme Allied Commander Europe (SACEUR) on related enablement issues.[33] Its responsibilities encompass operationalizing the multi-domain reinforcement and sustainment network within SACEUR's area of responsibility, integrating efforts with civilian, governmental, and non-governmental stakeholders, and delivering a comprehensive logistical operational picture to support Alliance operations.[33] The command emphasizes the motto "Enable – Deploy – Sustain," focusing on rapid force movement, theater preparation, and long-term logistical support to deter aggression and respond to threats.[34] Headquartered in the Wilhelmsburg Barracks, JSEC employs approximately 450 military personnel and civilians drawn from 30 NATO member nations.[33] Command is held by a three-star lieutenant general; as of October 10, 2024, Lieutenant General Kai Rohrschneider of the German Army leads JSEC, having succeeded Lieutenant General Alexander Sollfrank.[35] During the change-of-command ceremony, SACEUR General Christopher G. Cavoli stated that "JSEC turned the Reinforcement and Sustainment Network from a concept to reality," underscoring its pivotal role in bolstering NATO's deterrence posture.[35]