 Complete the following phrase:  , 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 Russias 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 