After Otto Warmbier, detained for more than a year in North Korea, returned home this week in a coma, the Trump administration is looking into ways to stop other Americans from going there.

The State Department currently warns Americans against travel to that country, but Secretary of State Rex Tillerson has signaled he may go further.

"We have been evaluating whether we should put some type of travel visa restriction to North Korea," he told a House Foreign Affairs Committee hearing Wednesday. "We have not come to a final conclusion, but we are considering it."

Fred Warmbier, Otto Warmbier's father, told reporters that his 22-year-old son is "a young, thrill-seeking, great kid" who was on a trip organized by a Chinese-based company called Young Pioneer Tours.

"They advertise it as the safest trip ever," he said Thursday. "But they provide fodder for the North Koreans, and my son happened to become fodder for the North Koreans."

The travel company says on its website that North Korea is "extremely safe!" A Young Pioneer Tours official told a news site that focuses on the region that only one person — Otto Warmbier — has ever been arrested among the 8,000-plus international travelers who have taken part in the company's tours.

It is highly unusual for the U.S. government to restrict the ability of Americans to go abroad.

"Those toughest restrictions on travel and tourism right now only really apply to Cuba," says former Treasury Department official Elizabeth Rosenberg. She says there are plenty of restrictions on what Americans can do in countries that face U.S. sanctions — like North Korea or Iran. But U.S. citizens are not banned from travel to either place.

It would take an act of Congress to impose a full-on travel ban. But, according to the State Department, the secretary of state can unilaterally impose a "geographic travel restriction." None are in effect now, but such a restriction means U.S. passports are invalid "for travel in, through or to" a country with "armed hostilities," at war with the U.S. or posing "imminent danger to the public health or physical safety of U.S. travelers."

But, says Rosenberg, "Putting in place the kind of restrictions that would require U.S. citizens to seek a license to go to North Korea — most of that falls to Congress to do."

South Carolina Rep. Joe Wilson co-sponsored a House of Representatives billto do just that, even before Warmbier's release. The Republican congressman says he wants to make sure the Treasury Department does not issue licenses for tourism to North Korea.

"If there are humanitarian efforts that are being conducted, that's fine," he says. "But tourism only really backs up a totalitarian regime."

Wilson was part of a congressional delegation visiting North Korea back in 2003. Wilson describes what he saw as a Potemkin village.

"It appears to be exotic to go to the country, but it's all staged," he says. "People don't need to go because there is nothing real. While I was there, it was clear to me that the people on the street, the people we met, the tours that we had, were not real."

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