The Pentagon has delivered a stark warning directly to the White House that the military “will not be politicized” following the administration’s efforts to hide the USS John McCain during President Donald Trump’s trip to Japan.

The Pentagon’s message contradicts claims Sunday by acting White House chief of staff Mick Mulvaney that attempts to hide the USS McCain to assuage Trump’s feelings were “not unreasonable.”

Acting Defense Secretary Patrick Shanahan on Friday ordered his chief of staff, Eric Chewning, to speak with the White House military office to “reaffirm his mandate that the Department of Defense will not be politicized,” Shanahan spokesman Lt. Col. Joseph Buccino told The Associated Press Sunday. The message was delivered.

Shanahan revealed to journalists that the White House request was made directly to officials of the Navy’s Seventh Fleet, CNN reported. Shanahan, who spoke to reporters as he flew to South Korea Sunday, said he had not talked to the president about the controversial issue.

The U.S. Navy confirmed Friday that the White House Military Office wanted to “minimize the visibility” of the USS John McCain when Trump was in Japan because of the contentious relationship between the president and the late Arizona GOP Sen. John McCain. The ship is named for McCain, a decorated Navy veteran, as well as for his father and his grandfather, who were both admirals.

Shanahan also told reporters that he had a private phone conversation with McCain’ wife, Cindy McCain, about the situation, but did not reveal details.

The effort to hide or move the Navy ship was first reported by The Wall Street Journal last week. Trump said he knew “nothing” about the efforts, but said whoever was responsible for the effort was “well-meaning.”

Shanahan told reporters he won’t call for an investigation by the Pentagon’s internal watchdog “right now” because “nothing was carried out” to hide the USS McCain, despite White House requests.

But Shanahan is still looking into what happened. He plans to talk to Navy officials again when he returns to Washington. “How did the people receiving the information — how did they treat it?” Shanahan intends to determine, he told reporters. “That would give me an understanding on the next steps” to take, he added, the AP reported.

Shanahan said nothing was done to hide or move the ship. A tarp over the name (a photo of which appeared in the Journal) was removed before Trump’s visit, according to Shanahan. He said the tarp was initially erected for “hull preservation” during ship repairs.

Ship personnel — whose uniform hats carry the name of the USS McCain — were given a 96-hour shore leave during Trump’s visit. But Shanahan has said that was not connected to the White House request.

Mulvaney shrugged off concerns about the extraordinary incident on NBC’s “Meet the Press” Sunday and said it would be “silly” to think anyone would be fired for trying to hide a Navy ship and its personnel because of a political rift and a miffed president.

He speculated that some young member of the advance team took it upon himself to arrange moving the ship to make the president happy, which was “not an unreasonable thing to do,” he said.