By Park Si-soo



The United States has officially set September 1 as the start of a ban on its citizens' traveling to North Korea.

"The Department of State has determined that the serious risk to United States nationals of arrest and long-term detention represents imminent danger to the physical safety of United States nationals traveling to and within the Democratic People's Republic of Korea (DPRK)," read the restriction that appeared Wednesday (local time) on the U.S. government's Federal Register.

"All United States passports are declared invalid for travel to, in, or through the DPRK unless specially validated for such travel."

An exemption was noted for approved humanitarian travel and for journalists in some circumstances.

The ban will remain in effect for one year unless it's revoked by U.S. Secretary of State Rex Tillerson, according to AFP.

The travel ban was first announced last month in the wake of the death of American student Otto Warmbier who fell into a coma after being imprisoned by Pyongyang during a tourist visit there.