The U.S. government will ban American citizens from traveling to North Korea, citing safety and security concerns. The State Department confirmed the new restriction on Friday, after Young Pioneer Tours, which organized Otto Warmbier's fateful visit to North Korea, announced the pending move.

Warmbier's trip to the pariah nation ended in detention, imprisonment and a catastrophic head injury that resulted in his death after being released and deported to the U.S. last month.

The "serious risk" of further detentions prompted Secretary of State Rex Tillerson to authorize "a geographical travel restriction on all U.S. citizen nationals' use of a passport to travel in, through, or to North Korea," State Department spokeswoman Heather Nauert said.

The restriction will become official 30 days after a notice is published in the Federal Register next week, she added.

"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," Nauert said.

According to a statement that Young Pioneer Tours posted to its website, the new policy will include the threat of canceling the passport of any American who violates the ban.

Another travel company that operates in North Korea, Lupine Travel, tells NPR that while it hasn't been contacted directly, "all we've heard is that apparently the Swedish Embassy have told a couple of other agencies that the ban is imminent."

The Swedish Embassy in Pyongyang operates as a conduit between the U.S. and North Korea, which do not maintain diplomatic relations.

Up to now, the U.S. policy has been that it "strongly recommends against all travel by U.S. citizens to North Korea."

News of the ban comes on the heels of North Korea's launching a new website that seeks to promote tourism to the country that has been at odds with much of the international community over its nuclear and missile programs.

As NPR's Colin Dwyer reported, "At least 16 Americans have been arrested by North Korean authorities in the past decade, according to the State Department — and that includes 'those who traveled independently and those who were part of organized tours.' "

Details of the travel ban that were provided by Young Pioneers match those supplied by Koryo Tours, another group that organizes visits to North Korea.

"This news has been expected but nevertheless is something of a shock," Koryo Tours said in a statement, "and we're sorry for anyone who had planned a trip or who had hoped to visit and who now will not be permitted to do so."

News of the pending ban comes one month after Warmbier, 22, died shortly after his return to the U.S. from a North Korean prison.

The college student had been sentenced to 15 years in prison and hard labor for allegedly trying to steal a propaganda poster. He was arrested during a trip that was organized by Young Pioneer Tours, which said in June that it will no longer take Americans to North Korea.

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