The United States has detained more than 83,000 foreigners in the four years of the war on terror, enough to nearly fill the National Football League largest stadium. The administration defends the practice of holding detainees in prisons from Afghanistan to Guantanamo Bay as a critical tool to stop the insurgency in Iraq, maintain stability in Afghanistan and get known and suspected terrorists off the streets. Roughly 14,500 detainees remain in US custody, primarily in Iraq. The number has steadily grown since the first CIA paramilitary officers touched down in Afghanistan in the fall of 2001, setting up more than 20 facilities including the "Salt Pit," an abandoned factory outside Kabul used for CIA detention and interrogation. In Iraq, the number in military custody hit a peak on Nov. 1, according to military figures. Nearly 13,900 suspects were in US custody there that day - partly because US offensives in western Iraq put pressure on insurgents before the October constitutional referendum and December parliamentary elections. The detentions and interrogations have brought complaints from Congress and human-rights groups about how the detainees - often Arab and male -are treated.