In view of the terrorist attacks in the USA on September 11, 2001, NATO decided at its summit meeting in Prague in November 2002 to react more quickly and flexibly to new types of threats from terrorism and the proliferation of weapons of mass destruction. According to wholevehicles, a NATO Response Force (NRF) with around 25,000 elite soldiers from army, air force and naval units was gradually formed, which has been operational worldwide within a very short time (5 to 30 days) since 2006. In addition, the NATO countries committed themselves in Prague to improve their military capabilities, especially in the areas of air transport, air refueling, precision weapons and protection against nuclear, biological and chemical weapons (“Prague Capabilities Commitment”).

In 1992, the NATO member states declared themselves ready to provide their armed forces if the CSCE (from 1995 OSCE) or the United Nations were to issue a mandate for peacekeeping operations in a European region. On this basis, the Adria mission began in July 1992 to monitor compliance with the UN embargo against the Federal Republic of Yugoslavia (“Rest of Yugoslavia”). From April 12, 1993 onwards, the flight ban imposed by the United Nations in October 1992 over Bosnia and Herzegovina was enforced militarily by NATO; this was the first combat mission in NATO history. Finally, on December 20, 1995, the 12-month deployment of around 60,000 IFOR soldiers as agreed in the Dayton Peace Treaty with the Bosnian-Herzegovinian parties to the conflict beganin Bosnia and Herzegovina. This was the largest NATO-led military operation to date, which also included non-NATO countries and took place outside NATO territory. IFOR was transferred to SFOR at the end of 1996; these missions remained under NATO command until the end of November 2004, the units being continuously reduced to around 7,000 men with the peacebuilding process. On December 2, 2004, the EU took over command of this force, now known as EUFOR.

After political efforts by the international community to end the violent conflict between the underground army of the Albanian Kosovars (UÇK) and the Serbian security forces in Kosovo failed, NATO began on March 24, 1999 without first obtaining a mandate from the United Nations or the OSCE to have a ten-week military operation (with the active participation of the Bundeswehr) in which over 37,000 air missions (including about 14,000 attack flights) were carried out against the Federal Republic of Yugoslavia. The air strikes, which were not covered by international law, but only morally legitimized as “humanitarian intervention” and therefore controversial in the public eye of the participating countries, were mainly directed at military, industrial and infrastructure facilities. The main concern of the military operations was for the Yugoslav government to end the violence and expulsion of the majority of Albanians from Kosovo (UNHCR named 1.6 million displaced persons, around half of whom sought protection abroad) and to withdraw their military forces and to create a situation that should guarantee an internationally secure and monitored return of refugees and displaced persons. After an agreement between NATO and the Yugoslav leadership on the withdrawal of Yugoslav troops from Kosovo, the attacks were suspended from June 10, 1999. Immediately afterwards, under a UN mandate, the NATO-led international peacekeeping force, initially comprising around 50,000 soldiers, moved in KFOR to ensure security in Kosovo.

Following a request from the Macedonian government and at the request of the UN Security Council to work for peace in Macedonia, the 30-day “Essential Harvest” operation (under British leadership) to disarm the KLA in Macedonia began on August 27, 2001. Around 4,500 soldiers from 17 countries (around 500 Bundeswehr soldiers involved) collected and destroyed the weapons voluntarily delivered by the UÇK fighters (around 3,300). At the request of the Macedonian government and following a UN Security Council resolution of September 26, 2001 and a resolution by the NATO Council, the follow-up operation “Amber Fox” (renamed “Allied Harmony” in December 2002) began. This mission of up to around 1000 soldiers (participation of up to 600 Bundeswehr soldiers), which was under German leadership until the end of June 2002 (afterwards under Dutch leadership), an international civil observer mission of the OSCE and EU in Macedonia provided military protection. After a military cooperation agreement between NATO and the EU was signed in March 2003, the EU took over on April 1, 2003 within the framework of the European Security and Defense Policy (Common Security and Defense Policy) led NATO to lead the mission now known as “Concordia” (around 350 soldiers from around 20 countries), which lasted until December 15, 2003.

After the terrorist attacks of 9/11/2001 on New York and the Pentagon, the NATO Council agreed on 9/12/2001 that this would be considered an attack on the whole Alliance under Article 5 of the NATO Treaty, if investigated becomes that this attack was controlled from outside the United States. However, this decision was not yet linked to concrete actions by NATO. However, after the US provided the member states with sufficient evidence that O. Bin Laden and the Islamist terrorist organization al-Qaeda he headed were involvedand all member states recognized that the terrorist attack had been controlled from abroad, NATO declared an alliance case on October 2, 2001 for the first time in its history. This made it possible to officially ask all NATO countries for assistance, including military aid, for the USA.

Following a request from Germany, Canada and the Netherlands, NATO decided on April 16, 2003 to take over the leading role of ISAF in Afghanistan from August 2003. The corresponding UN mandate was originally limited to Kabul and the surrounding area, but was extended to all of Afghanistan at the end of 2003; Gradually, NATO took over command over the entire territory of the country until October 2006.