President Barack Obama's decision to place a timeline for withdrawal of troops from Afghanistan raised concerns in both parties.

While the war is deeply unpopular, the fear has been that giving a definite date for withdrawal provides a strategic advantage to enemy combatants.

Vice President Joe Biden explained the firm deadline on withdrawal of U.S. troops in a way that makes sense.

"Unless you set a timeline, Baghdad, in the case of Iraq; and Kabul, in the case of Afghanistan, will not step up," Biden said. "They're happy to let us continue to do the job. The only way they step up is to say, ‘Fellas, we're leaving. We've trained you. Step up, step up.'"

Presidential nominee Mitt Romney won't say when he would bring troops home from Afghanistan, but it is instructive that he would still have U.S. troops in Iraq.

Biden defended the administration's decision to let Afghan troops carry the load in the most dangerous regions.

"That's right, because that's the Afghan responsibility," Biden said. "You'd rather Americans be going in doing the job instead of the (Afghan) trainees?"