Washington: The White House has added further mystique to a cryptic comment made by President Donald Trump that it was the "calm before the storm".

"We're never going to say in advance what the president is going to do," White House spokeswoman Sarah Sanders said on Saturday, adding that the comment wasn't a cheeky attempt to mess with the press.

On Friday, as President Donald Trump posed for a formal photo with his top military commanders and their spouses in the State Dining Room at the White House, he pointed to the leaders gathered around him and asked the small group of reporters standing before him: "You guys know what this represents?"

"Tell us," shouted out one of the reporters unexpectedly summoned to witness this photo session.