Yonhap via Reuters

Kenneth Bae, 44, was convicted of "hostile acts" against North Korea.

An American tour operator sentenced to 15 years of hard labor in North Korea has begun his sentence at a “special prison,” state media reported Wednesday.

Kenneth Bae, 44, stood trial last month accused of “hostile acts” against the repressive regime.

Bae, who is from Washington state, was convicted of an attempt to topple the government through “state subversion” according to a brief report on the Korean Central News Agency's website.

“Pae Jun Ho, an American citizen, started his life at a special prison on Tuesday,” the report said, referring to him by his Korean name.

He is one of at least three other U.S. citizens who are also devout Christians to have been detained by North Korea in recent years.

While North Korea's constitution guarantees freedom of religion, in practice only sanctioned services are tolerated.

Washington state Rep. Cindy Ryu told The Herald newspaper in December that Bae might have been doing missionary work in North Korea.

"Many of us are third- and fourth-generation Christians and many of our pastors are originally from North Korea," Ryu said. "We want to visit our home country, but in North Korea you cannot say you are a missionary."

A Facebook page has been set up titled “Remember Ken Bae, Detained in North Korea.”

Related:

• North Korea: Detained American tourist has 'admitted his crime'
• Detained American, Internet freedom on agenda as Google boss visits North Korea
• Full North Korea coverage from NBC News

The U.S. diplomat accused of spying in Russia joins a small group of Americans who have been publicly branded spies while overseas.

Keystone/Getty Images

Francis Gary Powers, pilot of the U-2 spy plane which crashed in Russia, appears before a Senate Armed Forces Committee in Washington holding a model of a U-2 in March 1962.

Their alleged transgressions range from piloting a spy plane into enemy territory to darting over a border in the wilderness. Some of them were returned to the U.S. after diplomatic intervention; some are still waiting to learn their ultimate fate:

Francis Gary Powers: The U-2 pilot parachuted into history on May 1, 1960, when a Russian missile shot down his spy plane. The cover story was that it was a weather plane, but after months of interrogation by the KGB, Powers publicly confessed to espionage and was sentenced to 10 years in prison.

He served less than two years, though, after the U.S. and Russia agreed to a spy swap. When he returned to the States, he found himself under fire for failing to activate the self-destruct mechanism on the U-2 or use a cyanide capsule before his capture, according to his son's website.

Cleared of any wrongdoing during a congressional inquiry, he was later awarded several medals -- but not until 20 years after he was killed in a helicopter accident while working as a pilot for KNBC in Los Angeles.

Vincent Kessler/Reuters

American businessman Edmond Pope, accompained by his wife Cheri, gives a thumbs-up to the press assembled on a balcony at the American Hospital of Landstuhl in Germany after he flew in from Moscow on Dec. 14, 2000.

Edmond Pope: It took 40 years after the Powers case for another American to be convicted of spying in Russia. Pope was a U.S. businessman working on defense projects when he was accused of obtaining classified torpedo designs from a Moscow professor. Pope said he had no idea the plans were off-limits.

His 2000 trial — which featured his defense lawyer delivering a closing argument in verse — ended with a guilty verdict and 20-year sentence. Within days, President Vladimir Putin had pardoned him, citing his poor health.

The retired naval intelligence officer always denied being a spy. "I'm not James Bond," he insisted after his release.

Laura Ling and Euna Lee: The two journalists traveled to China in 2009 to film a documentary for Current TV and were arrested after North Korea claimed they had crossed the border. With tensions between Washington and Pyongyang running high, the two women were convicted of "hostilities" against North Korea and illegal entry and sentenced to 12 years of hard labor.

Ling and Lee were granted amnesty after former President Bill Clinton intervened on behalf of the White House. They later said that they had spent only seconds on the North Korean side of the border before returning to Chinese territory and that soldiers chased them and dragged them back.

Robyn Beck/AFP – Getty Images

Freed U.S. journalists Euna Lee, left, and Laura Ling embrace family members after being released from North Korea at the airport in Burbank, Calif., on Aug. 5, 2009.

Shane Bauer, Josh Fattal and Sarah Shourd: A visit by three hikers to a waterfall on the border of Iran and Iraq turned into a two-year international saga. Iranian guards arrested the trio — who were working in Kurdistan at the time — and accused them of espionage.

Shourd was released in 2010 for health reasons but the two men were convicted in 2011 and sentenced to eight years. They became a cause celebre and were released a month later after the government of Oman posted nearly $1 million in bail to secure their freedom.

They maintain that they were not spying and don't even know if they actually crossed into Iran by accident. "From the very start, the only reason we have been held hostage is because we are American," Fattal said when he and Bauer were back on U.S. soil.

Press TV via AP

American hikers Shane Bauer, left, Sarah Shourd, center, and Josh Fattal, sit at the Esteghlal Hotel in Tehran, Iran, on May 20, 2010.

Timothy Tracy: Venezuelan authorities arrested the California filmmaker last month and accused him of being a U.S. government agent and paying right-wing groups to destabilize the new government of leftist President Nicolas Maduro.

The 35-year-old's family said he was in Venezuela only to make a documentary. He was heading back to the U.S. for his father's 80th birthday when he was detained at the airport in Caracas, relatives told the Associated Press.

Obama called the accusations that Tracy is a spy and that the U.S. is trying to incite civil war "ridiculous."

Tracy family via AP

This undated family photo released April 25, 2013, shows Timothy Tracy inside of a vehicle in Venezuela.

Kenneth Bae: The American businessman was arrested in North Korea in November and sentenced last month to 15 years of hard labor for "hostile acts."

Yonhap via Reuters

Video released in Seoul by Yonhap News Agency on May 2, 2013, shows a portrait of U.S. citizen Kenneth Bae.

Friends say Bae, 44,  was a tour operator who ran excursions from China and a devout Christian who had traveled to the North several times with an eye toward helping orphans there.

The U.S. has demanded his release, and basketball star Dennis Rodman, who claims to be friends with North Korean leader Kim Jong-Un, tweeted that he was going to bat for Bae.

Alan Gross: The U.S. Agency for International Development subcontractor is serving a 15-year prison sentence in Cuba after being convicted of leading a "subversive project" by smuggling satellite equipment to the communist-run island.

James L. Berenthal/AP

Jailed American Alan Gross poses for a photo during a visit by Rabbi Elie Abadie and U.S. lawyer James L. Berenthal at Finlay military hospital in Havana, Cuba, on Nov. 27, 2012.

He was nabbed during his fifth trip to Cuba in 2009 while in possession of a SIM card that blocks tracking of satellite phone signals. It is not available on the open market, according to the AP, but is used by the Defense Department, State Department and CIA.

Gross, 64, claimed during that trial that he was doing humanitarian work and was duped into bringing in contraband. His lawyer has called him a pawn in the decades-old feud between the U.S. and Cuba.