Paul Whelan, a 49-year-old Michigan man detained in Russia on allegations of spying, asked President Trump for help on Thursday in winning his release.

“Mr. President, we cannot keep America great unless we aggressively protect and defend American citizens wherever they are in the world,” Whelan told reporters during his appearance in a Moscow courtroom, according to the Washington Post.

“Mr. President, we cannot keep America great unless we aggressively protect and defend American citizens wherever they are in the world.” — Paul Whelan, American businessman detained in Russia

PAUL WHELAN, FORMER US MARINE SUSPECTED BY RUSSIA OF BEING A SPY, TO REMAIN JAILED UNTIL MAY

He also asked the president to express support for his cause on Twitter, according to reports.

Whelan, a former U.S. Marine, was arrested by Russian officials in December after he was handed a flash-drive with classified information that his lawyer has insisted Whelan was unaware of.

Whelan’s brother, David, has insisted Paul Whelan is not a spy and said in January it “sounds like he was set up.”

Whelan was working for Michigan-based auto supplier BorgWarner at the time of his arrest, the Detroit Free Press reported.

If convicted on espionage charges, Whelan could face 20 years in prison in Russia.

In the past, Whelan has complained of poor conditions in the Moscow jail where he is being kept. But he told reporters Thursday that the conditions had somewhat improved, the Associated Press reported.

Whelan has also sought help from Canada, Britain and Ireland – other nations where he holds citizenship, according to the Washington Post.

President Trump has neither spoken publicly nor tweeted about Whelan’s case, the Free Press reported, but the newspaper says U.S. National Security Adviser John Bolton and other Trump administration officials have spoken out against his continued detention, for which they claim the Russian government has produced no evidence.

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Whelan previously worked for Kelly Services, which maintains offices in Russia. He received a “bad conduct” discharge from the Marines, according to his official military personnel file obtained by Fox News. His dates of service were listed as May 10, 1994, to Dec. 2, 2009.

David Whelan says Paul fought in Iraq on multiple tours of duty.

Fox News’ Greg Norman and the Associated Press contributed to this story.