President Donald Trump’s insistence that his $600 million White House ballroom is justified because of the security upgrades it will bring is undermined by the fact that the complex already has a secret bunker, according to former officials.

The Washington Post cites three ex-officials who point to the existence of the nuclear-proof underground base as a basis for rejecting Trump’s case for proceeding with his pet project.

The bunker was commissioned in response to the 9/11 attacks and completed during Barack Obama’s tenure to keep the commander-in-chief safe.

It is reportedly situated 60 feet below street level, is accessible by private elevator, stores a month’s supply of food, has its own air supply system and is intended to shield its inhabitants from a range of threats, including the blast of a weapon of mass destruction.

It was itself constructed as a successor to the existing Presidential Emergency Operations Center in the basement of the East Wing, which was built to protect Franklin D Roosevelt in the Second World War and served to safeguard first lady Laura Bush and vice president Dick Cheney when al-Qaeda struck 25 years ago.

The unnamed former officials told The Post the arguments put forward for the bunker during the War on Terror are similar to those being made by the Trump administration now to explain the need for the new ballroom, raising questions about whether the latter is really essential.

“The East Wing Modernization Project is inextricably tied to the security of the president, the White House grounds and the certain security infrastructure assets,” White House spokesman Davis Ingle countered in a statement to the Post.

“Recent events such as the foiled attack on the historic UFC Freedom 250 event at the White House proves exactly why the East Wing Modernization Project is severely needed for large scale events, which include drone proof structures and drone ports among other critical security enhancements.”

The Independent has reached out to the White House for further comment.

The fate of the construction project currently sits with the U.S. Supreme Court. Chief Justice John Roberts issued an order Friday allowing work to continue while his bench considers an emergency appeal arguing that it must be halted unless congressional approval is granted.

Both a U.S. district judge and a federal appeals panel have found that the support of a majority of lawmakers in the House of Representatives and Senate is required before the undertaking can proceed but did make an exception for the planned subterranean military complex.

White House Deputy Chief of Staff Stephen Miller said in an August filing that the proposed complex “serves continuity-of-government interests by ensuring that the president and senior national security staff are able to operate from a protected facility during any attack on the nation’s capital.”

Army Secretary Dan Driscoll has similarly claimed: “Securing this reinforced subterranean node guarantees uninterrupted command and control in place.”

Driscoll called it “a nondiscretionary prerequisite to ensure the president can maintain continuity of government, uninterrupted operations, and effectively exercise National Command Authority during an attack or global crisis.”

Lawyers for the White House told the Supreme Court earlier this month the complex is 65 percent complete and that a 250-strong construction crew was working on it 20 hours per day, seven days a week to get it done.

Trump himself has meanwhile claimed that opposition to the project is “disloyal” and attacked the National Trust for Historic Preservation, the organization tasked by Congress with preserving D.C. institutions and landmarks, for challenging the ballroom in court, suggesting their lawsuit risked compromising national security.

“I said the problem with the suit – I told them this – is that we have many military things in this ballroom, and ideally, they shouldn’t be revealed,” he complained in the Oval Office last week.

“But now they are revealed, so the world knows about it.”