Canada's elite JTF2 unit joined American special forces in Afghanistan shortly after the al-Qaida attacks on September 11, 2001. Canadian forces joined the multinational coalition in Operation Anaconda in January 2002. On April 18, 2002, an American pilot bombed Canadian forces involved in a training exercise, killing four and wounding eight Canadians. A joint American-Canadian inquiry determined the cause of the incident to be pilot error, in which the pilot interpreted ground fire as an attack; the pilot ignored orders that he felt were "second-guessing" his field tactical decision. Canadian forces assumed a six-month command rotation of the International Security Assistance Force in 2003; in 2005, Canadians assumed operational command of the multi-national Brigade in Kandahar, with 2,300 troops, and supervises the Provincial Reconstruction Team in Kandahar, where al-Qaida forces are most active. Canada has also deployed naval forces in the Persian Gulf since 1991 in support of the UN Gulf Multinational Interdiction Force.