US President returns home from last foreign trip

Following his final foreign press conference in Peru's capital Lima, Obama headed to the airport, where he spoke with a few people at the foot of Air Force One.

He then jogged up the steps of the presidential plane, turned around to give two brief waves and ducked inside one last time.

After landing at Andrews Air Force Base just outside Washington, Obama took the Marine One helicopter to the White House.

Obama's trip was dominated by the deep uncertainty Trump has unleashed about the world order with his attacks on free trade and the US role as global "policeman."

Obama said an increasingly borderless world has brought "historic gains in prosperity, education and health," but acknowledged globalization had both winners and losers.

It was an awkward trip for Obama, who campaigned against Trump as his successor but had to reassure US allies on the future.

He asked the world to treat the brash billionaire as he himself vowed to do: "Wait and see."

At the same time, he sought to pre-empt his successor on some key issues.

He claimed his signature trade agreement in the Asia-Pacific, the TPP, was still alive despite Trump's vows to kill it, and said he wanted to reach a deal on the Ukraine crisis before leaving office.

He said Trump's presidency would probably be far different from his candidacy, and have to accommodate external forces.

"Once you're in the Oval Office, once you begin interacting with world leaders, once you see the complexities of the issues, that has a way of shaping your thinking," Obama said.