As dawn broke, Air Force One touched down at Joint Base Andrews in Maryland outside the US capital and Trump, wearing an open collar white shirt, waved as he walked down a red-carpeted staircase and got into a limousine.

Trump was apparently tweeting even as the plane landed.

He praised himself for backing a woman who won a Republican primary Tuesday in South Carolina, defeating a Trump critic.

Trump also repeated an earlier tweet of his criticizing Robert de Niro, who used an expletive to blast the president at the Tony Awards. In the tweet Trump called the actor "a very Low IQ individual."