Did the US support rebel groups that later formed ISIS?
The Islamic State of Iraq and Syria (ISIS) began as an offshoot of the Islamist group al-Qaida, which formed to oppose the 1979 Soviet invasion of Afghanistan. The U.S., then engaged in the Cold War, funnelled weapons and money to al-Qaida to aid its opposition. The Soviets were eventually driven out of Afghanistan and the sharia-based Taliban regime was established. Al-Qaida went on to commit acts of terrorism against the U.S., including 9/11.
More recently, the U.S. armed Syrian rebel groups fighting against the Assad regime during the Syrian Civil War. One of these groups, al-Qaida in Iraq, later combined with other Islamist groups to form ISIS. A 2017 study from weapons tracker Conflict Armament Research found ISIS possessed "significant quantities" of U.S.-supplied weapons and ammunition.
While U.S.-backed efforts beginning in 2014 reclaimed all ISIS-controlled territory, the group remains active in the Middle East.