LIMA, Peru – Defense Secretary Leon Panetta lashed back at Afghan President Hamid Karzai on Friday, saying the Afghan leader should say thank you now and then to the allied forces who are fighting and dying there, rather than criticizing them.

Panetta was responding to Karzai’s complaints Thursday that the U.S. is failing to go after militants based in Pakistan, and instead is concentrating on the insurgents in Afghanistan.

“We have made progress in Afghanistan because there are men and women in uniform who have been willing to fight and die for Afghanistan’s sovereignty,” Panetta snapped, as he spoke with reporters traveling with him to South America. “Those lives were lost fighting the right enemy – not the wrong enemy – and I think it would be helpful if the president, every once in a while, expressed his thanks for the sacrifices that have been made by those who have fought and died for Afghanistan, rather than criticizing them.”

The uncharacteristic shot from Panetta comes as tensions between the two countries have escalated over the increase in insider attacks, where Afghan security forces or insurgents dressed in their uniforms have turned their guns on coalition troops. And it raises the temperature on the heels of the announcement that, as of last weekend, 2,000 U.S. troops had lost their lives in the war.

At the same time, however, there is persistent frustration with the insurgents, including members of the Haqqani network, who wage attacks against coalition forces in Afghanistan and can then retreat to their safe havens in Pakistan. U.S. officials have repeatedly pressed Islamabad to more forcefully go after the insurgents, including Haqqani factions in and around North Waziristan.

But the U.S. also routinely uses drone strikes across the border into Pakistan to target and kill militants.

Karzai spoke at a press conference, complaining that if NATO troops want to go after terrorists they need to go where their safe havens are. And he also expressed frustration that Afghan forces aren’t getting the weapons they need from NATO allies, suggesting Afghanistan might have to go to other countries such as China and Russia to get them.