Barack Obama calls for seamless transition for US military to Donald Trump

President Barack Obama called for a smooth handover of control of the US military to incoming commander in chief Donald Trump, as the outgoing president met today with military leaders for the last time.

"We've got to make sure that during this transition period that there is a seamless passing of the baton, that there's continuity," Obama said.

He said it was critical to ensure that "we are doing everything we can to make sure that the next president will benefit from the same kinds of outstanding advice and service that these people around the table have provided me."

Obama's comments as he sat down with the Joint Chiefs of Staff and the military's combatant commanders came amid concerns in military and diplomatic circles about how Trump may handle national security challenges.

Over the last few days, Trump has disputed the US intelligence community's assessments about Russian hacking, insisted without explanation that North Korea won't develop a nuclear weapon that could hit the US and questioned the worth of the United Nations.

Obama pointed to a handful of conflicts that Trump will inherit when he takes office on January 20, including the fight against the Islamic State group in Syria and in the Iraqi city of Mosul, the biggest IS stronghold in Iraq and last major Iraqi city where the extremist group still has control.

He also noted that the conflict in Afghanistan "is still active."

In praising the military, Obama appeared to call attention to traditions that Democrats are most concerned that Trump may not uphold.

Trump has nominated retired Marine Corps Gen. James Mattis for defense secretary despite the prohibition on recently departed military members running the civilian-led Pentagon, and at one point in the campaign, Trump called for reinstating waterboarding and other harsh interrogation techniques.

Obama said he was optimistic about the country's future because the military upholds "the values of rule of law and professionalism and integrity, and recognises our constitutional structure and maintains strict adherence and respect for civilian authority and democratic practises in determining how we use the awesome force of the American military."

The president later today was to be honoured at a farewell ceremony at Joint Base Myer-Henderson Hall, a short drive from the White House. He was to receive several awards and to be feted by members of the US Army, Navy, Marine Corps, Air Force and Coast Guard as the US Army Band plays.