Acting Defense Secretary Patrick Shanahan said Friday he’d asked his chief of staff to “look into” a reported request from the White House to move the USS John S. McCain "out of sight" during President Donald Trump's recent state visit to Japan, adding that the Pentagon's job is to "not become politicized."

“I did ask my chief of staff to look into the matter,” Shanahan told reporters during a news conference in Singapore, noting that his request was different from a "formal investigation."

Shanahan said his chief of staff had already conducted a "quick” and “not exhaustive” search for any emails about the reported request and that “we received none.”

“Our business is to run military operations and not become politicized,” Shanahan said. “Our job is to run the military,” he added.

“I would not have moved the ship," Shanahan said.

The Wall Street Journal reported Wednesday that it had reviewed an email to Navy and Air Force officials dated May 15 that included the direction "USS John McCain needs to be out of sight" for Trump's Japan visit. CNBC has also obtained the email. NBC News has not reviewed the email.

Trump said Wednesday night on Twitter: "I was not informed about anything having to do with the Navy Ship USS John S. McCain during my recent visit to Japan." Trump again denied any involvement on Thursday, but said whoever made the request was "well meaning."

Trump was a fierce critic of the ship's namesake while the Arizona senator was alive, and he has continued to criticize him even after the Republican lawmaker died more than nine months ago.

The Defense Department has disputed parts of the Wall Street Journal's account. Cmdr. Nate Christensen, a spokesman for U.S. Pacific Fleet, said "all ships remained in normal configuration during POTUS' visit," using a common acronym for "president of the United States." And Joe Buccino, a spokesman Shanahan, told NBC News Thursday that Shanahan wasn't aware of the directive, "nor was he aware of the concern precipitating the directive."