"Congress has taken keen interest in U.S. relations with Pakistan, especially as related to counterterrorism and U.S. foreign assistance. The terrorist attacks of September 2001 transformed U.S.-Pakistan relations virtually overnight. After more than a decade under broad U.S. sanctions for its nuclear proliferation activities, and later for a military coup, Pakistan became a key ally in U.S.-led efforts to combat Islamist militancy and extremism. Pakistan has been a leading recipient of U.S. assistance for nearly 15 years, having received more than $20 billion in economic, security, and humanitarian aid, and military reimbursements. The Administrations of President George W. Bush and President Barack Obama have sought close engagement with Pakistani leaders. […] Pakistan is a haven for numerous Islamist extremist and terrorist groups, and successive Pakistani governments are widely believed to have tolerated and even supported some of these as proxies in Islamabad's historical tensions and conflicts with neighbors. […] In January 2015, Secretary of State John Kerry led a U.S. delegation for the 5th session of the bilateral U.S.-Pakistan Strategic Dialogue to review progress in the existing five Working Group areas (economic and finance; defense; law enforcement and counterterrorism; security, strategic stability, and nonproliferation; and energy). In April, the State Department approved the possible $952 million sale to Pakistan of U.S.-built attack helicopters and missiles, suggesting that the Administration intends to continue bolstering Pakistan's capacity to combat militants in its rugged and semi-autonomous western regions."
CRS Report for Congress, R44034
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html