U.S.-Pakistan relations strained since raid that killed Osama bin Laden . The U.S. has accused Pakistani officials of helping the Haqqani network and other militant groups launch attacks in Afghanistan. Pakistanis objected to raid and U.S. drone strikes . Prime Minister Nawaz Sharif set to visit White House on Wednesday .
U.S.-Pakistan relations strained since raid that killed Osama bin Laden . Obama administration began withholding some aid in 2011 . Pakistanis objected to raid and U.S. drone strikes . Prime Minister Nawaz Sharif set to visit White House on Wednesday .