A senior US Defense Department official says the United States will reduce the number of troops in Afghanistan and Iraq to about 2,500 each by mid-January.
Acting Defense Secretary Christopher Miller said on Tuesday that the move will implement President Donald Trump's orders to reposition US forces in the two countries.
Miller said the drawdown will be completed by January 15.
Media reports say about 4,500 US troops are in Afghanistan and 3,000 in Iraq.
Trump has repeatedly said he will bring back US soldiers from abroad.
Miller last week replaced former Defense Secretary Mark Esper who was fired by Trump.
Esper was reportedly opposed to the withdrawal of US troops as he believed it could lead to regional instability and disrupt peace efforts.
Some Republicans are also against a withdrawal which they say could worsen the situation.