Two senior Islamic State leaders were killed in U.S. and coalition airstrikes in northern Iraq over the last week, U.S. officials said Thursday, as Defense Secretary Chuck Hagel approved orders for several hundred troops to deploy to Iraq to train Iraqi forces.

According to one of the U.S. officials, airstrikes killed a key deputy of Abu Bakr al-Baghdadi, the leader of the Islamic State militants, and one of Baghdadi's military chiefs. A third militant, described as a midlevel leader, was also killed.

Word of the deaths came after Hagel signed orders Wednesday for the first group of U.S. troops to go to Iraq as part of the recent decision to deploy 1,500 more American forces to the country. - AP