Defence Secretary Chuck Hagel said in a statement he "strongly" supports Obama's decision to maintain a limited US troop presence in Afghanistan, adding that it will "help ensure that Al Qaeda cannot reconstitute itself" in the country.
Obama announced the drawdown plan two days after he made a surprise visit to Afghanistan where he met with US commanders and forces.
Obama also emphasised that the presence of US troops is tied to the signing of the Bilateral Security Agreement (BSA) with the Afghan government. Outgoing Afghan President Hamid Karzai has refused to sign the accord.
Obama said he is "hopeful" of the signing of the BSA as the two final candidates in the runoff presidential election have each indicated that they would sign the agreement promptly after taking office.
Calling the end of US mission in Afghanistan a "new chapter in American foreign policy", Obama said it will allow the US to redirect some of the resources saved by wars to "respond more nimbly to the changing threat of terrorism, while addressing a broader set of priorities around the globe."
