The United States is rejecting demands from Pakistani officials that American personnel abandon a military base used by the CIA to stage drone strikes against suspected militants. US personnel have not left the remote Pakistani military installation known as Shamsi Air Base and there is no plan for them to do so, said a U.S. official. That base is neither vacated nor being vacated,” the official said. The information was confirmed by a second U.S. official. The US declaration that drone operations in Pakistan will continue unabated is the latest twist in a fraught relationship between security authorities in Washington and Islamabad, which has been under increasing strain for months.