WASHINGTON (AP) — Lawyers representing the federal government argued Friday that a court could not stop construction of a White House ballroom it was already underway and because of the sensitive security concerns they say the structure is meant to address.

Attorney Yaakov Roth, speaking during an exchange with U.S. Appeals Court Judge Patricia Millett, said only Congress could stop the $400 million project. The administration has been asking the court to allow it to press on without congressional approval.