(AP) – White House Chief of Staff Susie Wiles and FBI Director Kash Patel personally oversaw an aggressive leak investigation after disclosures about security concerns involving a Qatari-gifted aircraft intended for use as Air Force One, according to CNN.

The report said some administration officials were asked to surrender their cellphones at the White House as investigators sought to identify the source of leaks concerning the aircraft’s security capabilities. Investigators also sought information from officials who traveled with President Donald Trump or were involved in the trip.

According to CNN, Patel delayed a planned trip to Chicago and spent about seven hours working alongside Wiles from the West Wing as they directed the investigation.

The leak probe became public after the Justice Department subpoenaed four New York Times journalists who reported on the aircraft’s security shortcomings. The newspaper has said it will challenge the subpoenas in court, while press freedom advocates criticized the move as a threat to First Amendment protections.

The investigation followed reports that Trump altered travel plans during a NATO trip after officials concluded the retrofitted Qatari Boeing 747 did not yet provide the same level of security as the existing Air Force One aircraft. Trump has denied security concerns prompted the change.