In his advisory to top commanders Wednesday, Gen. Joseph F. Dunford Jr. said Karzai's remarks "could be a catalyst for some to lash out against our forces -- he may also issue orders that put our forces at risk," The New York Times reported.
The command threat advisory was issued as backlash grows against Karzai's public denunciations of the United States, including a speech in which he suggested that his government might act unilaterally to ensure control of the Bagram prison if the United States delays its handover.
The advisory specifically mentioned Karzai's comments concerning Bagram, warning commanders to be on guard against insider attacks by Afghan forces against Western troops, as well as Taliban violence.
Brig. Gen. Stephen M. Twitty, the head of communications for the military in Kabul, told the Times a more general threat advisory typically would have gone out in April, but recent events pushed it earlier.
"This is prudent," Twitty said. "It's making sure the force is seeing the same thing we're seeing. It's our job to alert the force."
Karzai's comments on Bagram is the latest public statements and positions critical of the United States, including banning Special Operations forces from a key province and suggesting the Taliban and the United States were essentially working together keep each other in Afghanistan.
An Obama administration official told the Times Wednesday commanders on the ground were taking steps appropriate for the situation. The official also said that while many in the administration were "obviously unhappy" with Karzai's comments, the current military assistance plan for Afghanistan wouldn't be derailed.
In Kabul, representatives from 14 political parties conducted a news conference to denounce the president's stance.
"All these remarks may destroy our relations with the international community, and especially America, and lead to the isolation of Afghanistan again," said Faizullah Zaki, the spokesman for Gen. Abdul Rashid Dostum, an Uzbek leader and warlord who campaigned for Karzai in his 2009 election and later fell out with him. "We are calling on the president to stop doing this because we believe it is not in our national interest."