(CNN) -- Some U.S. commanders in Afghanistan have ordered heightened security in the wake of recent events, a senior defense official told CNN Monday.
Some of the precautions were put in place in the wake of the violence that followed the burning of copies of the Quran by U.S. troops last month, the official said. Sunday's fatal shooting of 16 Afghan civilians allegedly by American soldier have added to concerns.
The precautions could include, for example, adding a second U.S. soldier to watch towers, where before there was one American and one Afghan on watch, the defense official said. American and Afghan forces live together on many of the smaller bases and outposts, and on some of these the United States has instituted a 24-hour guard of their barracks.
The official would not confirm the specific procedures in place at each forward operating base, but said, "Those changes are all within the right of any commander to institute. I won't deny that several may have felt it was necessary to do so."
The official said battalion and even company commanders at combat outposts are "given the discretion and authority to weigh their individual security concerns and take appropriate action."
He said the security changes "are not coming from the top," meaning they are not directed by NATO's International Security Assistance Force or the Pentagon.
The top commander of U.S. and NATO forces, Gen. John Allen, said the troops should continue in their mission, according to another military official, Capt. John Kirby. While force protection is "always a priority," there has not been an increase in protection forces overall, Kirby said.
Allen "gave direction to his commanders on Saturday right after hearing about (the shooting) incident to continue to engage, to keep getting out there, to keep partnering with the Afghan forces," Kirby said in an interview with CNN on Monday. "It's absolutely vital that we try to move past this. The only way to move past this is to continue to engage and to operate with the Afghan partners."