At least four people have been killed in a U.S. drone strike in northwestern Pakistan. U.S. officials say the attack targeted militants. It is unclear if any civilians were killed. It was at least the third U.S. drone strike inside Pakistan since Pakistani lawmakers called for an end to the attacks in March. It also comes as U.S. and Pakistani officials continue talks over the unresolved NATO attack that mistakenly killed 24 Pakistani soldiers last year. The United States has refused Pakistani calls to apologize in return for the reopening of NATO supply routes into neighboring Afghanistan.