The administration no longer feels it can meet the January 2010 deadline Obama set for closure soon after taking office. Obama says he isn't disappointed about missing the deadline, but has realized that things move slower in Washington than he expected.
Obama says the timeline for closing Guantanamo will depend on cooperation from Congress. About 220 detainees remain at the prison, and the administration must decide how to prosecute some in U.S. courts and turn others over to other countries.
Obama also said his upcoming strategy in Afghanistan will "put us on a path towards ending the war" and that his goal is not to pass the conflict on to the next president.
Obama also declined to say he trusted Afghan President Hamid Karzai, offering praise to Karzai for holding his country together but saying: "He has some strengths, but he has some weaknesses."
"I'm less concerned about any individual than I am with a government as a whole that is having difficulty providing basic services to its people," Obama said in his latest blunt assessment of the Karzai government, whose competence is an essential part of a U.S. war effort now in its ninth year.
Obama is expected soon to announce a revamping of the U.S. strategy in Afghanistan and Pakistan. He is likely to send thousands more troops into Afghanistan to stabilize the deteriorating security there.
Many times, the White House has said Obama will reveal his decision in the next few weeks. Obama did so again in a series of TV interviews, saying his announcement will come by year's end.
Asked if his decision will end the war, Obama said: "This decision will put us on a path towards ending the war." Obama inherited the Afghanistan conflict and suggested he wants to be the one to end it.
"My preference would be not to hand off anything to the next president," Obama said. "One of the things I'd like is the next president to come in and say, `I've got a clean slate."'
But there will be no drawdown of U.S. forces anytime soon. Obama has sought to repeatedly assure the world that the U.S. is not pulling out of Afghanistan, a case he plans to make to the American public.
Obama promised to tell the nation "in very clear terms, what exactly is at stake, what we intend to do, how we're going to succeed, how much it's going to cost, how long it's going to take."
He has a tough sell. Polling shows most Americans do not favor sending more troops to Afghanistan.
Meanwhile, details of Obama's deliberations and the views of some of his national security aides have appeared for weeks in news stories. The president echoed the concerns of Defense Secretary Robert Gates about those "leaks," saying he is probably angrier than Gates about them.
"We have these deliberations in the Situation Room for a reason, because we are making decisions that are life and death...," Obama said. "For people to be releasing information during the course of deliberations when we haven't made final decisions yet, I think is not appropriate."
Obama made his comments during his trip to Asia in interviews with Fox News Channel, NBC News, CNN and CBS News.