2001 NATO Article 5 contingency
| Company type | Intergovernmental military alliance |
|---|---|
| Industry | Defense and security |
| Founded | April 4, 1949 |
| Headquarters | Brussels , Belgium |
Area served | North Atlantic region |
Key people | NATO Secretary General (2001) Baron Robertson |
| Products | Collective defense, military operations |
The North Atlantic Treaty Organization (NATO) invoked an Article 5 contingency through decisions made by the North Atlantic Council between September 12 and October 2, 2001, following the September 11 attacks in the United States. This invocation of NATO’s collective defense clause was initiated by NATO itself, without a formal request from the U.S., despite reservations expressed by Germany, Belgium, Norway, and the Netherlands. To date, this remains the sole occasion in NATO’s history where Article 5 has been activated.
Two limited-scale military operations were approved: Operation Eagle Assist, which involved deploying aircraft to North American airspace; and Operation Active Endeavour, a primarily symbolic naval mission conducted in the Mediterranean Sea. The United States, doubtful about NATO’s operational capacity, chose not to seek additional Article 5 support and NATO did not take part in the subsequent American invasion of Afghanistan, although some member countries participated independently.
Subsequent to a request from the United Nations, NATO deployed the International Security Assistance Force (ISAF) to help stabilize Afghanistan after the invasion. ISAF was predominantly composed of U.S. troops operating under U.S. command.
Background
On September 11, 2001, coordinated attacks by Al-Qaeda targeted both civilian and military locations within the United States. The simultaneous 2001 anthrax attacks were initially suspected to be connected to Al-Qaeda.
As a member of NATO, the U.S. is protected under Article 5 of the Washington Treaty, which permits collective defense measures—including military action—by member states if a signatory located north of the Tropic of Cancer is attacked.
September 12 resolution
On the night of September 11, 2001, NATO Secretary General Baron Robertson proposed to U.S. Secretary of State Colin Powell that invoking Article 5 would send a strong political message in reaction to the attacks. Powell responded that while the U.S. would not formally request this step, it would support NATO taking the initiative independently.
Within NATO staff, opinions were split on whether Article 5 was applicable to these events. During deliberations on September 12, several member states voiced opposition: Germany viewed it as premature to consider military measures; the Netherlands and Belgium pushed for softer language in the draft resolution, causing delays; and Norway sought to distance itself from endorsing the measure.
The North Atlantic Council unanimously adopted a resolution on September 12 that conditionally activated Article 5 pending confirmation that the attacks were orchestrated from abroad. The declaration specified that if foreign direction was established, the attack "shall be regarded as an action covered by Article 5 of the Washington Treaty."
Discussions on alliance action
No immediate military response followed NATO’s resolution on September 12.
Former NATO official Michael Rühl observed a dismissive attitude from Washington toward its allies, describing it as a "don't call us, we'll call you" approach. In interagency talks about involving NATO forces in the planned U.S. military campaign, General Tommy Franks reportedly rejected participation due to unfamiliarity with allied troops. On September 20, 2001, U.S. Deputy Secretary of State Richard Armitage informed the North Atlantic Council that his presence was solely informational and that he was "not here to ask for anything."
October 2 resolution
On October 2, 2001, the North Atlantic Council confirmed that the attacks on September 11 were carried out by forces external to the United States. Privately, U.S. officials downplayed this declaration, indicating that NATO had no immediate combat strategy prepared for Afghanistan.
The next day, NATO launched two military initiatives:
- Eagle Assist involved deploying 830 aircrew members and seven NATO aircraft to bolster U.S. and Canadian air defense efforts under Operation Noble Eagle. This support allowed the U.S. Air Force to redeploy assets overseas. Twelve NATO countries contributed personnel. The operation continued until May 2002.
- Active Endeavour was a naval mission in the Mediterranean designed to intercept possible shipments of weapons of mass destruction. While largely symbolic due to the absence of credible threats, it also played a role in securing Greece during the 2004 Olympic Games.
Additional actions included granting comprehensive overflight permissions for U.S. military flights across NATO airspace and tightening security measures around American bases located within allied nations.
Aftermath
NATO's invocation of Article 5 was intended to rally member countries behind the U.S.-led campaign against Al Qaeda; however, no NATO-wide forces were assigned to Operation Enduring Freedom. Instead, the United States accepted individual contributions from 14 NATO members and other allies, ranging from small contingents to substantial deployments such as the United Kingdom’s infantry brigade and naval task group. The U.S. hesitated due to its perception of NATO’s Kosovo intervention as an ineffective "war by committee," while European allies viewed this stance as American "arrogance."
In response to a United Nations request, NATO formed and deployed the International Security Assistance Force (ISAF) to provide stability in Afghanistan after the invasion. Although ISAF operated under NATO’s umbrella, it was predominantly staffed by U.S. forces under American command until their withdrawal in 2014—seven years prior to the U.S. military’s exit in 2021 and the Taliban’s subsequent resurgence.
The activation of Article 5 in 2001 remains unique as the sole instance of NATO’s collective defense clause being invoked.