, requiring member states to come to the aid of any member state subject to an armed attack, was invoked for the first and only time after the September 11 attacks, after which troops were deployed to Afghanistan under the NATO-led ISAF. The organization has operated a range of additional roles since then, including sending trainers to Iraq, assisting in counter-piracy operations and in 2011 enforcing a no-fly zone over Libya in accordance with UN Security Council Resolution 1973. Article 4, which merely invokes consultation among NATO members, has been invoked five times following incidents in the Iraq War, Syrian Civil War, and Russia's annexation of Crimea. This annexation led to strong condemnation by NATO nations and the creation of a new "spearhead" force of 5,000 troops at bases in Estonia, Lithuania, Latvia, Poland, Romania, and Bulgaria. At the subsequent 2014 Wales summit, the leaders of NATO's member states formally committed for the first time to spend the equivalent of at least 2% of their gross domestic products on defence by 2024, which had previously been only an informal guideline. In 2014, only 3 out of 30 NATO members reached this target (including the US); by 2020 this had increased to 11. Taken together, in 2020, the 29 non-US member states had six consecutive years of defence spending growth, bringing their average spending to 1.73% of GDP. NATO did not condemn the 2016–present purges in Turkey. As a result of the Turkish invasion of Kurdish-inhabited areas in Syria, Turkey's intervention in Libya and the Cyprus–Turkey maritime zones dispute, there are signs of a schism between Turkey and other NATO members. NATO members have resisted the UN's Nuclear Weapon Ban Treaty, a binding agreement for negotiations for the total elimination of nuclear weapons, supported by more than 120 nations.