Karoline Leavitt refused to provide further details about the military building a “big complex” underneath the new $400m White House ballroom under construction.

While speaking with reporters aboard Air Force One, Donald Trump said members of the military are involved in the construction, and hinted at it being a new bunker.

“The ballroom essentially becomes a shed for what’s being built under the military, including from drones, including from any other thing,” the president said, adding that the windows will be “bulletproof.”

During Monday’s briefing, the White House press secretary would not be drawn on the topic.

“I cannot tell you more about [the complex] as a matter of fact, however, the military is making some upgrades to their facilities here at the White House, and I’m not privy to provide any more details on that this time.”