Celebrity doctor Mehmet Oz is under fire from national security experts after a resurfaced photo showed him casting a ballot in Turkey’s 2018 presidential election.

Oz, a dual U.S-Turkish citizen, pledged to revoke his Turkish citizenship if elected to the U.S. Senate after initially saying he’d forego security clearances to maintain it.

Even though Oz claimed on the campaign trail to have “never been politically involved in Turkey in any capacity,” he voted in Turkey’s most recent presidential election, according to his spokesperson, Brittany Yanick, who confirmed the photo’s authenticity.

Yanick defended Oz’s vote by distinguishing casting a ballot from being “actively engaged” in the Turkish government. “Voting in an election is far different from being actively engaged in the political work of the Turkish government, which Dr. Oz has never been involved with,” Yanick told ABC News. “There is no security issue whatsoever.”

Yanick added that Oz’s vote was a last minute decision while visiting Turkey’s consulate to discuss “humanitarian work on behalf of Syrian refugees in Turkey.” Oz reportedly voted for Muharrem Ince in his failed attempt to unseat Turkish leader Recep Tayyip Erdogan.

A former government attorney familiar with federal security clearances said that Oz’s 2018 vote “is problematic from a security clearance perspective.”

With Oz’s dual citizenship at the center of his candidacy for Senate, some national security experts are worried his Turkish ties would set off a “giant, flashing red light” for the civilian background check process.

As ABC News reported:

Elected officials are not subjected to the same level of scrutiny as civilians who seek security clearances for sensitive government work; once sworn-in, lawmakers are granted access to classified information, unless the executive branch denies them certain information.

But the background check process for civilians can also “provide a framework for analyzing whether someone is trustworthy or not,” according to Kel McClanahan, the executive director of National Security Counselors, a nonprofit public interest law firm. And for McClanahan, voting in another country’s election would set off a “giant, flashing red light.”

Oz reportedly maintains his Turkish citizenship to care for his mother in the country while she battles Alzheimer’s disease. However, Oz had to serve in the Turkish military to receive Turkish citizenship, which he did briefly during the early 1980s.

In addition to his vote in Turkey’s election, national security experts worry about his significant financial ties to the foreign country. Oz has hundreds of thousands of dollars in real estate holdings in Turkey, according to his financial disclosures. Oz even leases out one of his buildings for free to the Turkish Ministry of Education.

Apart from his real estate interests in the country, Oz also has an endorsement deal with Turkish Airlines, the country’s national airline. Oz appeared in a 2018 Super Bowl commercial for the airlines and most recently starred in a four-minute informercial detailing the airlines’ coronavirus safety protocols last year.

“Any single one of those would be enough to torpedo a [security] clearance,” McClanahan told ABC News. “Taken together, I would not put good odds on that person getting a clearance anywhere.”

Another foreign policy expert said that Oz, who promised to “be the harshest critic of Erdogan” in the Senate, would have no choice but to be friendly with Ergodan to maintain the Turkish Airlines brand ambassador position over the years.

“If you wanted to have a lucrative career as a spokesman for Turkish Airlines, you certainly couldn’t say anything negative about Erdogan,” said Nicholas Danforth, a non-resident fellow at the Hellenic Foundation for European and Foreign Policy.

Oz’s financial disclosures also drew criticism for his ties to China after he reportedly made millions of dollars doing deals with a company that produced its products in China.

Along with national security experts, members of the Armenian-American and Greek-American communities have expressed concerns about Oz’s Turkish ties. They fear that his ties to the country could potentially mainstream Armenian Genocide denial.

However, former President Donald Trump’s former Director of National Intelligence, Ric Grenell, said Oz’s understanding of Turkey is an asset when dealing with totalitarian leaders like Ergodan.

“It is frankly un-American to suggest that first- and second-generation Americans are unworthy or suspect to work as a U.S. official,” Grenell said. “They’ve seen fascism and totalitarianism and are actually more clear-eyed about what is at stake.”

Oz received the Trump endorsement last month ahead of Pennsylvania’s Republican Senate primary, which will occur on May 17.

Other experts lauded Oz for his transparency about his dual citizenship, noting that it would be more of a political risk than a national security risk.

“The fact that [Oz] has made no effort to conceal his dual citizenship counts in his favor,” said Federation of American Scientists senior analyst Steve Aftergood. “Voters will have an opportunity to decide whether or not it is of concern to them.”