President Obama said the toughest decision he had to make during his eight years in the White House was sending more troops to Afghanistan, especially after he promised to end the military's large presence in the country during the 2008 campaign.

"That was the first time in which I looked out at a crowd of West Point graduates and knew that some of those might not come back because of that decision," Obama said in an interview that aired Sunday on ABC News' "This Week."

In late 2009, Obama ordered about 30,000 additional troops to the war-torn country, making that years' total troop buildup in Afghanistan nearly triple what it was when he took office.

Obama announced his plans in a speech at West Point.

"Now, I had said from the start that I thought Iraq was a mistake, that we should have stayed focused on Afghanistan," Obama said on "This Week."

"I think it was the right decision because the Taliban at that point had gotten a lot of momentum before I'd gotten into office, partly because we hadn't been paying attention as much as we needed to to Afghanistan. And since that time we've been able to build up the Afghan security forces and stabilize it."