It was the first attack on the K1 base since December 27 BAGHDAD: A mortar shell slammed into an air base hosting US troops in northern Iraq late Thursday causing no casualties, two Iraqi security officias said. The shell struck the K1 Iraqi military air base in Kirkuk province, according to the security sources, who spoke on condition of anonymity because they were not authorized to brief the media. They provided no additional details. A rocket attack on the same base in December triggered a chain of retaliatory events that led to soaring US-Iran tensions and brought Iraq to the brink of war. On Thursday, Iraqi forces conducted a search of the perimeter of the base and discovered a launching pad and 11 unused missiles, a statement from Iraq’s military said. A rocket attack on K1 killed a US contractor on Dec. 27 and led Washington to conduct an airstrike that killed top Iranian Gen. Qassem Soleimani and senior Iraqi militia commander Abu Mahdi Al-Muhandis. The attack infuriated Shiite Iraqi lawmakers who voted to oust US troops from the country in a Jan. 3 Parliament session. Iran retaliated for Soleimani’s killing with a barrage of missiles that targeted two air bases hosting American troops in Irbil and Ain Al-Asad. Iran and the US have since refrained from further escalation, but the issue of American troops has monopolized Iraqi politics.