About once a month, the Central Intelligence Agency sends a fax to a general at Pakistan's intelligence service outlining broad areas where the US intends to conduct strikes with drone aircraft, the Wall Street Journal quoted US officials as saying. The Pakistanis, who in public oppose the programme, don't respond.
On this basis, plus the fact that Pakistan continues to clear airspace in the targeted areas, the US government concludes it has tacit consent to conduct strikes within the borders of a sovereign nation, according to officials familiar with the programme.
Representatives of the White House's National Security Council and CIA declined to discuss Pakistani consent, saying such information was classified. In public speeches, Obama administration officials have portrayed the US's use of drones to kill wanted terrorists around the world as being on firm legal ground. In those speeches, officials stopped short of directly discussing the CIA's drone programme in Pakistan because the operations are covert.