An American sentenced to 15 years of hard labor in North Korea at the end of last month was secretly performing missionary work, the North Korean government and some media outlets are saying.

Kenneth Bae, 44, a South Korean immigrant to the United States., was arrested in November.

The reasons for his detention have been unclear until this week, when the official [North] Korean Central News Agency accused him of bringing inflammatory material and anti-government students into the country.

KCNA, which reflects official North Korean policy and disseminates its propaganda, said Bae had with him included a National Geographic film made in 2007. It documents a clandestine visit by one of the magazine's reporters, according to NK News.

The Washington Post notes that what may have raised North Korea's ire was film portraying a visit to a Catholic church in Pyongyang.

The Post cited a report from the U.S. Commission on International Religious Freedom which reported an interview of a defector who said that the churches were fake and an elaborate show.

Bae is also accused of speaking against the government in lectures and recruiting 250 students into the city of Rason in order to oppose the regime.

The Rason area is a special economic zone.

OPERATION JERICHO

KCNA reported that Bae, who runs tour groups into North Korea from China, was really involved in a missionary project affiliated with Youth With a Mission (YWAM) called "Operation Jericho".

The city of Jericho was a city of which the Bible says, "No one came out and no one went it".

Bae entered China in 2006 apparently to do missionary work with YWAM. Once there, he formed a company called Nations Tours to do what he said were cultural exchanges.

In 2011 Bae spoke at the Korean Presbyterian Church in St. Louis and told of his work in China.

He said he was planning on doing the same kind of humanitarian work in North Korea that he was already doing.

"I know that Jesus wanted me to be a channel to the North", he said. "This year I'm working at take several short-term mission teams into North Korea."

In a note on the church's website, Bae wrote, "Several of us are getting ready to spread the Gospel from Pyongyang to Jerusalem."

"We plan to open up a base from which mobilization and missionary work can all be carried out from one location," he said.

John Geissler, a U.S.-based missionary, took a group to North Korea through Nations Tours on a business trip. "'We had hoped to begin production of detergent in China and export it to North Korea," he said in NK News.

MISSIONARY WORK

"Sometimes it takes a business to do missionary work", said Geissler.

Bae came to the U.S. in 1988 to attend the University of Oregon, according to Stuart Tomlinson of the Oregonian news site. His South Korean friends from those days, Dennis Kwon and Bobby Lee, have been working for his release.

"Knowing Kenneth from college, he is such a warm-hearted person, I can't imagine him breaking the law," said Kwon.

Friends and colleagues describe Bae as a devout Christian with a heart for orphans.

Kwon suggested he may have been arrested for taking pictures of orphans begging for food. "He probably couldn't walk away from what he saw," he said.

The U.S. government has called for Bae's release at a time tensions between the U.S. and North Korea, always high, have been at a fever pitch.

North Korea has threatened to annihilate the U.S. and has said that the armistice signed at the end of the Korean War is no longer valid.

Some commentators have speculated that Bae is a bargaining chip.

FORMER US PRESIDENTS

North Korea has detained several Americans over the years, prompting high profile visits from such people as former presidents Bill Clinton and Jimmy Carter in order to gain the release of a captive.

North Korea always often concessions in such cases, but Pyongyang has said that Bae will not be used in such a way.

Former NBA star Dennis Rodman, who knows North Korean leader Kim Jong Un from a controversial visit he made to the country in February, asked for Bae's release when he sent a message on Twitter this week.

He requested that Kim, purportedly a huge NBA fan, to "do him a solid" and free Bae.

North Korea reportedly has tens of thousands of Christian believers within its borders. Included in that number are those who are locked away in prisons.

Open Doors, a non-denominational Christian ministry which follows persecution around the world, listed North Korea on its "Watch List" for the ninth straight year.