Flynn waits for an elevator in the lobby at Trump Tower on Monday. (Drew Angerer/Getty Images)

Retired Lt. Gen. Michael Flynn, President-elect Donald Trump’s choice for national security adviser, railed during the campaign against Hillary Clinton for her reported mishandling of classified material as secretary of state. But according to U.S. Army records published Wednesday by the Washington Post, Flynn “inappropriately shared” classified information with foreign military officers in Afghanistan.

That was the conclusion of a secret 2010 U.S. military investigation, according to documents obtained by the newspaper under the Freedom of Information Act.

In 2010, military officials launched an investigation after receiving a tip from a Navy intelligence specialist alleging Flynn had inappropriately shared secrets while in Afghanistan.

According to a four-page summary of the probe published by the paper, the investigation concluded that during his tenure as deputy chief of staff for intelligence, Flynn shared “classified information with various foreign military officers and/or officials in Afghanistan without proper authorization.”

But it also determined no further action was warranted against Flynn, because he did not act “knowingly” and that “there was no actual or potential damage to national security as a result.”

The military report also noted “efforts to properly cleanse the foreign officer’s read-books,” the “keen attention to mission accomplishment in a coalition combat environment” and Flynn’s “exceptional qualifications and dedicated service.”

Representatives for Trump’s transition team did not immediately return requests for comment.

However, Flynn’s son, Michael Flynn Jr., tweeted that the Post’s story about his father was “fake news.” The younger Flynn was removed from the transition team earlier this month after spreading conspiracy theories, including the so-called Pizzagate story that apparently motivated a gunman to open fire inside a Washington, D.C., restaurant.

Related: Flynn Jr., who spread conspiracies, ‘no longer’ with transition

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At the Republican National Convention in July, Flynn assailed Clinton for putting “our nation’s security at extremely high risk with her careless use of a private email server,” leading the crowd in chants of “lock her up.”

“If I did a tenth, a tenth of what she did, I would be in jail today,” Flynn said in his convention speech.

Trump’s appointment of Flynn has drawn criticism from civil and human rights groups over his incendiary comments about Muslims and online embrace of conspiracy theories.

“Fear of Muslims is RATIONAL,” he tweeted in February, linking to a YouTube video that argued “Islamophobia is an OXYMORON since having a Phobia means having an IRRATIONAL FEAR.”

“There’s something going on in the Muslim world,” Flynn said in August. “Why do we have heightened security at our airports? It’s not because the Catholic Church is falling apart.”

And his appointment has drawn the ire of former colleagues who were puzzled when Flynn traveled to Moscow last year to appear alongside Russian President Vladimir Putin at a gala for the Kremlin-run channel RT.

During his visit, Flynn said he didn’t know whether the deadly 2013 sarin gas attack in Syria was conducted by the Russian-backed Syrian regime or staged.

“I really don’t know,” Flynn said. “I’m not going to sit here and tell you that I know. To have that level of knowledge or insight or detail of what an intelligence service is doing to do a false flag — who knows.”

Flynn later defended the trip, saying he was paid to attend as a speaker and used the opportunity to press Putin.

“I wanted to tell Russia to get Iran the hell of out the four proxy wars they’re involved in in the Middle East,” Flynn told Yahoo News.