US National Park Service lawyers cite materials that will be installed to make ‘heavily fortified’ facility

Donald Trump’s administration is arguing that a judge’s order to halt construction of a $400m White House ballroom creates a security risk for the US president as his team asks a federal appeals court to pause the ruling.

In a motion filed on Friday, US National Park Service (NPS) lawyers say that the federal judge’s order to suspend construction of the new facility is “threatening grave national-security harms to the White House, the president and his family, and the president’s staff”.