WASHINGTON – President Barack Obama will announce in his State of the Union address that 34,000 U.S. troops will be home from Afghanistan within a year, a senior administration official said Tuesday.

That's about half the U.S. forces currently serving there, and marks the next phase in the administration's plans to formally finish the war by the end of 2014. The U.S. now has 66,000 troops in Afghanistan, down from a peak of about 100,000 as recently as 2010.

The U.S. is still finalizing plans for the size and scope of its military presence after the war ends. The White House has said it would be open to leaving no troops in Afghanistan, though it's likely that a small presence will remain, in keeping with the Pentagon's preferences.