The U.S. defense secretary says Afghanistan's president needs to show the international coalition troops who are fighting and dying in his country some gratitude instead of criticizing them.

Leon Panetta was responding Friday to Afghan President Hamid Karzai's remarks Thursday that the U.S. is failing to go after militants based in Pakistan, and instead is concentrating on the insurgents in Afghanistan.

Panetta said “I think it would be helpful if the president every once and awhile expressed his thanks for the sacrifices that have been made by those who have fought and died for Afghanistan, rather than criticizing them.”

The defense secretary's remarks come as tensions between Washington and Kabul have escalated over the increase in insider attacks, in which Afghan security force members turn their guns on coalition troops.

There is also growing frustration with insurgents who stage attacks on coalition forces in Afghanistan and then retreat into Pakistan. While the U.S. has urged Pakistan to deal more forcefully with the retreating militants, the U.S. routinely uses drone strikes in Pakistan to target and kill militants.