Acting Defense Secretary Patrick Shanahan informed the White House that the U.S. military must not be politicized, following a move by aides to President Trump to obscure the USS John S. McCain from Trump’s view during a presidential visit to Japan.

“Secretary Shanahan directed his chief of staff to speak with the White House military office and reaffirm his mandate that the Department of Defense will not be politicized,” Lt. Col. Joe Buccino, a Pentagon spokesman, said in a statement, according to Reuters. “The chief of staff reported that he did reinforce this message,” Buccino said.