Otto Warmbier has been given 15 years hard labor in North Korea for crimes against the state.

The 21-year-old American student was arrested for trying to steal a propaganda sign from a hotel while visiting North Korea in January.

Otto Warmbier later appeared on state TV apparently confessing and saying a church group had asked him to bring back a “trophy” from his trip.

North Korea sometimes uses the detention of foreigners as a means of exerting pressure on its adversaries.

The 15-year sentence is high compared to those given to foreigners in the past.

North Korean state news agency KCNA said Otto Warmbier was convicted under an article of the criminal code relating to subversion. The verdict was handed down by the Supreme Court.

Otto Warmbier, a student at the University of Virginia, was arrested on January 2 as he was trying to leave North Korea. He was accused of committing “hostile acts”.

KCNA said at the time he had gone to North Korea “to destroy the country’s unity” and that he had been “manipulated” by the US government.

At the end of February, at a tearful press conference in Pyongyang, Otto Warmbier said he had “committed the crime of taking down a political slogan from the staff holding area of the Yanggakdo International Hotel”.

“The aim of my task was to harm the motivation and work ethic of the Korean people. This was a very foolish aim,” Otto Warmbier was quoted as saying.

He said it was the “worst mistake” of his life.

The sentencing comes a day after veteran US diplomat Bill Richardson met North Korean officials at the UN in New York to try to push for Otto Warmbier’s release.

Bill Richardson has previously been involved in negotiations to secure the release of Americans from North Korea detention.

North Korea has ramped up its hostile rhetoric in recent weeks, after the UN imposed some of its toughest ever sanctions.

The sanctions were a response to North Korea conducting its fourth nuclear test and launching a satellite into space, which was seen as a covert test of banned missile technology.

Pyongyang has also been angered by the US and South Korea carrying out their annual military drills, which this year involve some 315,000 personnel.