The State Department on Friday said Americans who seek to travel to North Korea will need a "special validation passport" after the "geographical travel restriction" on US citizens travelling there takes effect.

Spokeswoman Heather Nauert specified that exceptions may only be granted for "certain limited humanitarian or other purposes." She added that all other travel by Americans "to, through and in" North Korea will be prohibited.

The State Department intends to publish a notice of Secretary of State Rex Tillerson's decision in the Federal Register next week. The travel ban will then reportedly take full effect 30 days later.

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The decision to ban travel to North Korea follows the death of 22-year-old university student Otto Warmbier, who died in June after falling into a coma at a North Korean prison. The US government said it wanted to ban Americans from traveling there due to "the serious risk of arrest" they may face. 

Two tour operators that organize group trips to North Korea, Koryo Tours and Young Pioneer Tours, said they had been informed of the decision in advance. Young Pioneer Tours said that after the 30-day grace period while the law was taking effect, any US national  traveling to North Korea would have their passport invalidated by their government.

Americans who violate the restriction could also face a fine and up to 10 years in prison for a first offense.

Isolating North Korea

It wasn't clear how many Americans the move will effect, as the number of Americans who travel to North Korea is unknown. But Simon Cockerell, the Beijing-based general manager of the Koryo Tours, one of the leading organizers of guided tours to North Korea, said the ban would affect 800 - 1,000 Americans who visit North Korea annually.

The US has strongly warned Americans against traveling to North Korea for years, but has not until now prohibited it. Barring Americans from entering North Korea marks the latest US move to further isolate the hermit kingdom.

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The travel ban comes as the Trump administration seeks more effective ways to increase pressure on North Korea over its nuclear weapons program. Pyongyang's recent successful test of an intercontinental ballistic missile - has created even more urgency to stop North Korea before it can master putting a nuclear warhead on a missile capable of hitting the United States.

The case of Otto Warmbier

Young Pioneer Tours, based in the Chinese city of Xi'an, was the agency that had organized US student Otto Warmbier's trip to North Korea last year. During his stay he was arrested for allegedly trying to steal a propaganda poster from his hotel. He was charged with hostile acts against the state and sentenced to 15 years in a labor camp after a one-hour trial in March 2016.

In June 2017, he was released from North Korean captivity and returned to the US in a coma, where he died a week later. Warmbier had reportedly suffered severe neurological injury from an unknown cause while in custody. Relatives said they were told that he likely had been in a coma since shortly after he was sentenced.

Three other American nationals are currently being held by Pyongyang. Details on their condition remain unknown. The United States, South Korea and other countries have accused North Korea of using foreign detainees to bargain for diplomatic concessions.

ss/rt (AP, Reuters, dpa)