The reports, one on Afghanistan and one on Pakistan, say that although there have been gains for the United States and NATO in the war, the unwillingness of Pakistan to shut down militant sanctuaries in its lawless tribal region remains a serious obstacle. American military commanders say insurgents freely cross from Pakistan into Afghanistan to plant bombs and fight American troops and then return to Pakistan for rest and resupply.

The findings in the reports, called National Intelligence Estimates, represent the consensus view of the United States’ 16 intelligence agencies, as opposed to the military, and were provided last week to some members of the Senate and House Intelligence Committees. The findings were described by a number of American officials who read the reports’ executive summaries.