The Gulf War, in which A, B and D squadrons deployed, was the largest SAS mobilisation since the Second World War, also notable for the failure of the Bravo Two Zero mission. In Sierra Leone it took part in Operation Barras, a hostage rescue operation, to extract members of the Royal Irish Regiment. Following the September 11 attacks on the United States by al-Qaeda in 2001, 2 squadrons of 22 SAS, reinforced by members of both the territorial SAS units deployed to Afghanistan as part of the Coalition invasion at the start of the War in Afghanistan (2001–present), to dismantle and destroy al-Qaeda and to deny it a safe base of operations in Afghanistan by removing the Taliban from power in the War on Terror. The Regiment carried out Operation Trent, the largest operation in its history, which included its first wartime HALO parachute jump. Following the invasion, the Regiment continued to operate in Afghanistan against the Taliban and other insurgents until 2006, when its deployment to Iraq became its focus of operations, until 2009 when the SAS redeployed to Afghanistan.