An official identified as a "senior U.S. military source" said that the talks "focused on ways to better work together to defeat extremists on the border and to help Pakistan deal with its own internal threats from extremism."

The commanders met secretly this week on board the U.S.S. Abraham Lincoln, an aircraft carrier in the Indian Ocean. The participants included Adm. Michael Mullen, chairman of the U.S. Joint Chiefs of Staff, and the Pakistani Army chief of staff, Gen. Ashfaq Parvez Kayani.

U.S. leaders have recently acknowledged that the Taliban has begun carrying out military-style attacks in Afghanistan. They have been pushing Pakistan to crack down on the Taliban in the tribal areas bordering Afghanistan.

Pakistan said that the 23 fighters who died were killed in an airstrike and a clash on the ground in the Swat Valley.