The Pentagon sent a stern message to the White House over the weekend after it was confirmed officials directed the United States Navy to minimize the presence of the USS John McCain during President Donald Trump's recent visit to Japan.

What did the Pentagon say?

Acting Defense Secretary Patrick Shanahan directed his staff over the weekend to reaffirm that the U.S. military will not be "politicized," Reuters reported.

"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," Pentagon spokesman Lt. Colonel Joe Buccino said. "The chief of staff reported that he did reinforce this message."

While traveling to Seoul on Sunday, Shanahan reaffirmed his message to reporters accompanying him on the trip.

"There is no room for politicizing the military," Shanahan said.

What is the background?

On Saturday, the U.S. Navy confirmed the White House requested the USS John McCain be moved during Trump's visit to Japan, NBC News reported.

"A request was made to the U.S. Navy to minimize the visibility of USS John S. McCain, however, all ships remained in their normal configuration during the President's visit," Rear Admiral Charlie Brown, chief of information, told NBC.

According to Reuters, the request originated in the White House military office. Apparently, staffers believed the optics would not be good for the president since McCain was one of his biggest political rivals.

However, as Brown confirmed, senior Navy leadership refused comply with the request.

What is the White House saying?

On Sunday, White House chief of staff Mick Mulvaney downplayed the incident, calling the request "not ... unreasonable."