Washington (CNN) Acting Secretary of Defense Patrick Shanahan issued two internal memos to all Department of Defense personnel, service members and civilian employees Tuesday calling on Pentagon leaders to "reinforce the apolitical nature" of the US military, according to copies obtained by CNN.

Shanahan's memos follow recent reporting that the White House Military Office coordinated directly with the Navy's Seventh Fleet to have the USS John S. McCain hidden from view during President Donald Trump's visit to Japan last month. After the news surfaced, Shanahan told reporters that request was ultimately not carried out.

"Those of us privileged to serve our Nation, in and out of uniform, in the DoD must be the epitome of American values and ethics. Our mission, to protect and defend the Nation, is apolitical," Shanahan wrote in one of Tuesday's memos.

"I call on leaders at all levels in the Department to reinforce the apolitical nature of military and civilian service and professionalism, while ensuring all personnel remain free to exercise the responsibilities of citizenship as laws and regulations allow," he added.

Following the USS John McCain controversy, Shanahan repeatedly insisted that "there's no room for politicizing the military" -- a point he again emphasized in Tuesday's memos to DoD personnel.

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