Story highlights Exceptions will require special approval

US tourist Otto Warmbier died in June after being detained for 17 months in North Korea

Beijing (CNN) The US government will bar American citizens from traveling to North Korea because of "mounting concerns over the serious risk of arrest and long-term detention," the State Department said Friday.

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.

There will be exceptions, though they'll require special approval, Nauert said.

"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," she said. "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."