US military personnel lower the US flag at a memorial ceremony in honour of the 15th anniversary of the September 11, 2001 attacks on New York and Washington DC, at the International Security Assistance Force (ISAF) headquarters in Kabul on September 11, 2016. The United States marks the 15th anniversary of the 9/11 attacks on Sunday with solemn services to commemorate the victims of the deadliest terror strikes on US soil, which changed the world forever. It was the first foreign attack on the US mainland in almost two centuries and sparked US-led invasions of Afghanistan (2001) and Iraq (2003, where war rages on more than a decade later. / AFP / WAKIL KOHSAR (Photo credit should read WAKIL KOHSAR/AFP/Getty Images)
