The fact that two American journalists, Laura Ling and Euna Lee, have been sentenced to 12 years of hard labor in North Korea has focused attention on the network of brutal labor camps in that country which the State Department says hold an estimated 150,000 to 200,000 political prisoners.

Like many aspects of life in North Korea, relatively little is known about what life is like in the labor camps. In her introduction to a report on the camps by the U.S. Committee for Human Rights in North Korea, Anne Applebaum, an expert on the Soviet gulags, wrote that the testimony of former prisoners suggests that “the North Korean camps were built according to a Stalinist model” and “continue to be run that way.” Ms. Applebaum’s brief summary of the conditions is harrowing:

As in Stalin’s time, North Koreans are arrested for trumped-up political “crimes,” such as reading a foreign newspaper, singing a South Korean pop song, or “insulting the authority” of the North Korean leadership. As in Stalin’s time, North Korean prisoners — even children — are given ludicrous and impossible work “quotas” to fulfill and are subjected to brutal, irrational punishments. And, as in Stalin’s time, North Korea’s leadership doesn’t want anyone to know any of these details, since such revelations not only will damage their foreign reputation but also put their own regime at risk.

The complete text of the report, “The Hidden Gulag: Exposing North Korea’s Prison Camps,” assembled by David Hawk, is available online and includes testimonies from former prisoners and satellite photographs of camp sites.

A State Department report released in February, just a few weeks before Ms. Ling and Ms. Lee were arrested while filming a report for Current TV along North Korea’s border with China, said that throughout 2008: “Reeducation through labor, primarily through sentences at forced labor camps, was a common punishment and consisted of tasks such as logging, mining, or tending crops under harsh conditions. Reeducation involved memorizing speeches by Kim Jong-il.”

Another source of information on the camps is “The Aquariums of Pyongyang: Ten Years in the North Korean Gulag,” a memoir by Kang Chol-hwan, a North Korean defector. The New Yorker’s Philip Gourevitch wrote in 2003 that Mr. Kang, who was sent to the Yodok prison camp with his family when he was nine years old, “describes with something of Primo Levi’s quiet authority how the brutality of the gulag is the ultimate refinement of the North Korean system.”

Given how rare glimpses of life in the labor camps is, Mr. Kang’s account has been studied at the highest levels of government in the United States. In 2005 James Brooke wrote in a profile of Mr. Kang for The Times that after President George W. Bush read his book, “at the urging of former Secretary of State Henry A. Kissinger,” he was invited to the White House “for a 40-minute meeting with Mr. Bush, Vice President Dick Cheney and the national security adviser, Stephen J. Hadley.”

Mr. Brooke explained that the camp Mr. Kang grew up in “was run as a business enterprise, with gold mines, cornfields and logging operations operating entirely on unpaid prison labor.” Mr. Kang’s account of life there includes a description of public executions where prisoners were forced to hurl rocks at corpses, and yell, “Down with the traitors of the people!” As Mr. Brooke wrote, “Following the beliefs of the North Korean authorities that political deviance is hereditary, entire families were routinely incarcerated, and still are, recent defectors say.”

Video obtained by a Japanese television station and posted on YouTube, reportedly showing prisoners at the same camp where Mr. Kang was imprisoned, allows us to see what the perimeter of the camp looks like, but seems to underscore that we can only imagine what life is like inside the barbed wire for so many North Korean political prisoners.

That said, there are, apparently, even worse fates in North Korea than being sent to do hard labor and endure “re-education.” In 2007, my colleague Choe Sang-Hun explained, in an article about a North Korean named Shin Dong Hyok, who had escaped from the prison camp he was born in, that there are camps where prisoners have no hope of ever being released: