 On February 18, 2009, Obama announced that the U.S. military presence in Afghanistan would be bolstered by 17,000 new troops by the summer.Obama also ordered the expansion of airstrikes to include the organization of Baitullah Mehsud, the militant chief reportedly behind the 2007 assassination of Benazir Bhutto, as priority targets.The U.S. drone attacks in Pakistan, that were begun by President George W. Bush, have increased substantially since an expansion of the attacks was authorized by President Barack Obama in 2009.