Seen in a dark face mask, waving to crowds, the president’s motorcade rolled past before returning to the Walter Reed military hospital near Washington.

“We’re going to pay a little surprise to some of the great patriots that we have out on the street,” Trump said in a video posted to Twitter shortly before his appearance.

“I’m about to make a little surprise visit.”

Trump also said he “learned a lot about Covid” by “really going to school”, as he has battled the virus in hospital.

“This is the real school. This isn’t the ‘let’s read the books school’, and I get it, and I understand it, and it’s a very interesting thing,” he added.

Trump’s doctors said Sunday that he has “continued to improve”, adding that he could be discharged as early as Monday.