U.S. to bar Americans from visiting North Korea

The United States is set to forbid American citizens from traveling to North Korea in the wake of "mounting concerns over the serious risk of arrest and long-term detention."

The step comes after U.S. college student Otto Warmbier died following his captivity in North Korea.

Warmbier was arrested last year while on the sightseeing tour. After being held prisoner by North Korea for 17 months, Warmbier in June was handed over to the US in a vegetative state. He died a few days later in Ohio.

Secretary of State Rex Tillerson authorized a "geographical travel restriction" on all US nationals' use "of a passport to travel in, through, or to North Korea," State Department spokeswoman Heather Nauert said.

The notice will be placed in the Federal Register on Thursday -- 64 years to the day after a cease-fire agreement ended fighting in the Korean War -- and the restriction will go into effect 30 days after that.

"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. Individuals seeking to travel to North Korea for certain limited humanitarian or other purposes may apply to the Department of State for a special validation passport," she said.