Reuters reports President Barack Obama formally notified the U.S. Congress on Monday that he had authorized air strikes and humanitarian airdrops over the weekend in the Iraqi Shi’ite town of Amerli where Islamic State militants had trapped the civilian population. Iraqi security forces backed by Shi'ite militias on Sunday broke the two-month siege of Amerli and entered the northern town after the U.S. military carried out air strikes on militant positions and delivered emergency supplies to residents there. Obama said in a letter to congressional leaders he was notifying Congress of his decision under the long-standing War Powers Resolution, which gives presidents authorization for temporary military action. The operation was launched on Saturday. Obama chose to broaden the U.S. military role in Iraq amid an international outcry over the threat to the town’s mostly ethnic Turkmen population from Sunni militants.