Will Afghan killings speed up U.S. withdrawal?

(CBS News) - On CBS News' "Face the Nation," White House correspondent Norah O'Donnell and national security correspondent David Martin discussed the latest developments of Sunday's deadly rampage by a U.S. soldier in Kandahar province that killed at least 16 Afghan civilians.

Martin said the mass killing complicates a very fragile time in Afghanistan and Pakistan. He noted that supply routes through Pakistan are still closed after U.S. aircraft killed 25 Pakistani soldiers in a cross-border attack; he also reminded viewers about the Quran burning in February which sparked deadly riots.

"And now you have this, which is obviously going to be another setback," Martin said. "War is a huge undertaking. It can withstand a number of mistakes, but when they start to pile up and accumulate, [they create] an atmosphere of war weariness."

O'Donnell said calls for a quicker troop withdrawal might get louder.

"I bet you'll see more of that this week from Democrats who say, 'Why are we in Afghanistan? It's time to leave.' And it's coming at a time when this discussion is underway about pulling forces out," O'Donnell said.

In a campaign year, this will surely become an election-related issue, O'Donnell said. "This is going to be a difficult thing for President Obama to manage, and Republicans will have to talk about how they would do things differently and explain how they would position our forces in the coming year in Afghanistan."

Earlier in the program, Republican presidential candidate Newt Gingrich called for a withdrawal of U.S. troops.

President Obama began withdrawing 33,000 American troops in 2011, with a goal of having 68,000 troops in Afghanistan by the fall.

"I think you could see a significant draw-down after the fighting season and that's going to be part of this debate, this presidential debate about bringing U.S. troops home and out of Afghanistan," O'Donnell said.