Although 18 American citizens have been detained by North Korea over the past two decades (and ten since Kim Jong Un, its leader, took power five-and-a-half years ago), they have rarely been hurt.
Foreign travellers are typically held either on espionage charges or for “hostile acts” against the North Korean state—bilingual Bibles left in bathrooms, for example.
These prisoners are mainly kept as bargaining chips in the hope of negotiations.
Mr Warmbier's case will fuel growing calls in America for a ban on travel to North Korea.
About 1,000 Americans visit each year, roughly one-fifth of all tourists to North Korea.
Backers of a ban say that such tours do “nothing but provide funds to a tyrannical regime”.
Yet revenue from tourism, estimated at $30m-40m a year, is only a small sliver of even the North's backward economy.
Opponents of a ban say it would simply help North Korea shut out the outside world.
Even if travel restrictions are put in place, talks like those that secured Mr Warmbier's release may still continue, says Scott Snyder of the Council on Foreign Relations, an American think-tank.
China, with which America held security talks this week, is keen to promote dialogue over North Korea's quest to build nuclear missiles capable of hitting America.
Indeed, it will argue that growing tensions make talks more necessary than ever.
1.took power 执政；掌权
例句:He took power by lawful means.
2.travel to 前往
例句:He was too sick to travel to his son's side.
3.shut out 排除
例句:When the new baby comes along it is only too easy to shut out the others.
4.be keen to 渴望；热衷于
例句:They'll be keen to enhance their reputation abroad.