BAGHDAD (AP) Thousands of mourners chanting America is the Great Satan marched in a funeral procession Saturday through Baghdad for Irans top general and Iraqi militant leaders, who were killed in a U.S. airstrike.

Gen. Qassem Soleimani, the head of Irans elite Quds force and mastermind of its regional security strategy, was killed in an airstrike early Friday near the Iraqi capitals international airport. The attack has caused regional tensions to soar.

Iran has vowed harsh retaliation, raising fears of an all-out war . U.S. President Donald Trump says he ordered the strike to prevent a conflict . His administration says Soleimani was plotting a series of attacks that endangered American troops and officials, without providing evidence.

An official with the U.S.-led coalition in Iraq said it has scaled back operations and boosted security and defensive measures at bases hosting coalition forces in the country. The official spoke on condition of anonymity according to regulations.