The US is to ban its citizens from travelling to North Korea.
State Department spokeswoman Heather Nauert said in a statement that the ban would be published next week in the Federal Register, to come into effect 30 days later.
US officials linked the move to the death of jailed American student Otto Warmbier.
Once the ban is in effect, US citizens will need special validation to travel to or within North Korea.
Warmbier travelled to North Korea with Young Pioneer Tours. He was arrested in 2016 for trying to steal a propaganda sign and sentenced to 15 years in prison. He was returned to the US in a coma in June and died a week later.
Koryo Tours and Young Pioneer Tours, who both operate in North Korea, revealed on Friday that they had been told of the upcoming ban by the Swedish embassy, which acts for the US as Washington has no diplomatic relations with Pyongyang.
Rowan Beard, of Young Pioneer Tours, told the BBC the embassy was urging all US nationals to depart immediately.
He said the embassy was trying to check on the number of US tourists left in the country.
Nauert’s statement said: “Due to mounting concerns over the serious risk of arrest and long-term detention under North Korea’s system of law enforcement, the Secretary has authorised a Geographical Travel Restriction on all US nationals’ use of a passport to travelling through, or to North Korea.
“Once in effect, US passports will be invalid for travel to, through, and in North Korea, and individuals will be required to obtain a passport with a special validation in order to travel to or within North Korea.
“We intend to publish a notice in the Federal Register next week.
“The restriction will be implemented 30 days after publication.”
Rowan Beard said that the 30-day grace period would “give leeway for any [Americans] currently in the country as tourists or on humanitarian work”. (Courtesy BBC)