North Korea‘s missile and nuclear tests, its carefully scripted propaganda bluster, even its military threats: Far from the scattershot workings of a madman, most of this fits the playbook of a small, proud country well used to stoking tensions to get concessions it would otherwise not receive from surrounding big powers.

What happened to Otto Warmbier, an American college student who died just days after North Korea released him from detention in a coma, is far more difficult to make sense of.

It jars so strikingly with the fates of most past detained Americans that outside observers are left struggling not only with the mystery of what killed Warmbier but also with what his death means for attempts by Washington and its allies to stop North Korea’s pursuit of a nuclear-tipped ICBM that can target the U.S. mainland.

“The treatment of Otto Warmbier is beyond the pale of North Korea’s usual standards,” said John Delury, an Asia expert at Seoul‘s Yonsei University. “It’s worth a forceful response. The U.S. government should not just throw up its hands and say, ‘This is just how North Korea is.’ But how do you do that in a smart way where there is some modicum of accountability?”

What follows is a closer examination of one of the more perplexing and heart-rending developments in North Korea’s long, antagonistic standoff with its neighbors and Washington.

It may never be known, but there are some clues — as well as widespread speculation.

The University of Virginia student was medically evacuated from North Korea last week, more than a year after a court sentenced him to 15 years in prison with hard labor for allegedly trying to steal a propaganda banner.

North Korean diplomats at the United Nations had urgently requested a face-to-face meeting with U.S. officials in New York. During the June 6 meeting, Washington learned of Warmbier’s condition.

His family said it was told he fell into a coma soon after his March 2016 sentencing after contracting botulism and taking a sleeping pill. Doctors in Cincinnati said they found no active sign of botulism or evidence of beatings. They say he had severe brain damage but they don’t know what caused it.

Some observers believe that North Korea became worried because Warmbier’s condition suddenly worsened.

“North Korea sent him back to the United States before he died because more questions would have been raised about his death and the situation would have gotten worse if it had returned his dead body,” said Cheong Seong-jang, an analyst at the private Sejong Institute in South Korea.

Others believe it is unlikely that North Korea intentionally harmed Warmbier because he was valuable as a political pawn. Poor hygienic conditions, diet or bad medical care may have been responsible for a coma that North Korean doctors couldn’t handle.

Or maybe North Korea concealed his medical condition for so long in the hopes that he’d recover.

Some outside experts see an internal divide in North Korea between officials who believe solving the long standoff with Seoul and Washington is the best way to improve the country’s economy and international standing, and hard-liners who believe that outside pressure, isolation and animosity help keep the ruling Kim family in power by solidifying domestic support.

The last thing conservatives want, the argument goes, is curious American tourists talking with citizens and undercutting decades of propaganda that assures North Koreans that they are the envy of the world.

But North Korea has also consistently lobbied Washington for specific concessions that would need deep negotiations, something recent U.S. administrations have been reluctant to pursue because of the North’s weapons programs. North Korea’s demands include a peace treaty to officially end the Korean War and the removal of U.S. troops from the Korean Peninsula.

“I’m sure there are high-ranking North Koreans who regret what happened to Warmbier and who think this was a mistake,” Delury said. “You’ve got to capitalize on this, and influence their internal debates to get them to recognize and acknowledge what happened.”

Another reading is that Warmbier’s death may simply show a pattern of North Korean callousness and a lack of concern over diplomatic repercussions. Outside groups say North Korea tortures thousands of its own citizens at prison camps. And earlier this year the North was suspected of arranging the killing of the half-brother of leader Kim Jong Un with VX nerve agent at a Malaysian airport.

Outrage in the United States means that more pressure, not dialogue, is the more likely course. But some analysts believe negotiations could happen because of U.S. worries about the safety of the three other Americans still detained in North Korea.

South Korean President Moon Jae-in has been unable to pursue the engagement with the North he favors because of a string of North Korean missile tests. Warmbier’s death could make it even harder, although some analysts think Moon could offer talks with the North as a way to get other detainees out of North Korea.

“It’s unlikely that Washington and Seoul will let Warmbier’s death entirely derail their efforts at talks because North Korea’s nuclear weapons program is such a serious and immediate threat,” said Koh Yu-hwan, a North Korea expert at Seoul’s Dongguk University. Still, opponents will question whether such negotiations may give the North more time to expand its nuclear weapons program.

Delury said the Trump administration may try to pressure China to cut its large numbers of tourists to North Korea until the North apologizes and releases the other Americans.

Whether North Korea will actually respond to pressure or talks is unclear. The country may not worry about much of anything externally, even the death of a young tourist, until it reaches its goal of building a nuclear ICBM that can ease what it sees as decades of U.S. and South Korean hostility.