Gen. Frank McKenzie, a top U.S. commander for the Middle East, told reporters travelling with him that the mortar attack started a fire that was put out. He said no U.S. military personnel were injured, but one U.S. national had a minor injury but returned to work.

Tuesday's breach of the embassy compound in Baghdad, which caused no known U.S. casualties or evacuations, revealed growing strains between Washington and Baghdad, raising questions about the future of the U.S. military mission there.