A close call between Marine One and a commercial aircraft earlier this month may have been partly due to White House ballroom construction, a National Transportation Safety Board report says.

On August 4, the presidential helicopter—with Donald Trump inside—took off from the White House Ellipse, heading to Joint Base Andrews in Maryland. The New York Times reported the following day that Trump, 80, had come within 0.82 nautical miles—approximately 0.94 miles—and 700 feet vertically of a passenger jet, because air traffic controllers had not stopped flights at Ronald Reagan Washington National Airport in Virginia.

Now, a preliminary NTSB report viewed by that outlet says that Trump taking off from the Ellipse instead of the South Lawn—a change that was caused by the construction of his ballroom—could have contributed to communication issues.

According to the report, technicians “conducted a coverage analysis and determined that there was not adequate line-of-sight to ensure communications” from the Ellipse to the air traffic control tower “while construction was ongoing at the White House.” Technicians reported no documented history of problems prior to August 4, but helicopter crews and controllers had discussed spotty communications on July 30.

A controller missed multiple warnings from Marine One that it was about to take off. As a result, they cleared for takeoff an Envoy Air jet destined for Pensacola, Florida.

According to the NTSB report, the incident resulted in a breach of safety protocols. Federal rules state that aircraft must maintain a minimum separation of 1.5 nautical miles horizontally or 500 feet vertically.

Despite this, the White House has continued to insist that Trump was never “in harm’s way.”

“Marine One flights are piloted by the finest aviators in the world, and the White House maintains the utmost confidence in these patriots and other security officials who are responsible for ensuring the president’s safety,” spokesperson Kush Desai told the Daily Beast in a statement. “Although the president was at no point in harm’s way during the Aug. 4 momentary loss of separation, the White House continues to work with relevant military, F.A.A., and other security personnel to ensure the president’s continued safety.”

Not only is the ballroom under construction, but a helipad on the South Lawn is also in the works—a project that Trump wants completed in time for Chinese President Xi Jinping’s September visit.

Construction crews are also working to level the South Lawn so it’s flush with the helipad.

In the meantime, Trump has been taking a motorcade to the Ellipse each time he uses Marine One.

The ballroom, the subject of legal disputes that have reached the Supreme Court, initially was estimated to cost $200 million. But the price tag has since grown to $600 million—more than half of which taxpayers are expected to cover. The total cost of Trump’s White House projects, according to the Washington Post, is about $927 million.

Trump has been known to show off renderings of the ballroom, which he will reportedly name after himself. Last October, White House Press Secretary Karoline Leavitt acknowledged it was his “main priority.”