Updated at 5:45 p.m. ET

The parents of an American college student who died after more than a year in North Korean custody have sued North Korea, accusing the regime of torture and mistreatment.

Otto Warmbier was returned to the U.S. last June in a coma. He died soon afterward. A coroner concluded that his death was "due to an unknown insult more than a year prior to death."

North Korea has denied torturing Warmbier, whom they accused of trying to steal a poster and sentenced to 15 years' hard labor. Pyongyang says the student's coma was caused by botulism.

Cynthia and Fred Warmbier, his parents, say that's a lie.

In the lawsuit, filed Thursday in the U.S. District Court for Washington, D.C., they say North Korea "brutally tortured and murdered" their 22-year-old son.

The Cincinnati couple accuses the regime of hostage-taking, torture, extrajudicial killing, wrongful death, intentional infliction of emotional distress, and assault and battery.

"North Korea's conduct was willful, outrageous, extreme and dangerous to human life, and violates applicable criminal law and all international standards of civilized human conduct and common decency," the lawsuit states.

The Warmbiers are asking for punitive damages.

The lawsuit comes just weeks before President Trump is due to meet with North Korean leader Kim Jong Un, an extraordinary and unprecedented meeting. And it was filed just days after the administration announced that Mike Pompeo — then CIA director, now secretary of state — met with North Korea earlier this month.

In general, countries are immune from lawsuits in other countries. "We prefer that disputes between sovereigns really be resolved at the diplomatic stage, as opposed to the private civil litigation stage," law professor Stephen Vladeck of the University of Texas explained to NPR in 2016 . And then there's the question of reciprocity, he said: "Otherwise you'd have a race to the bottom where countries would hale each other into each other's courts."

But there are exceptions — including, in the U.S., an exception for countries designated as state sponsors of terrorism. That's what allowed Washington Post reporter Jason Rezaian to sue Iran for torture in 2016.

North Korea was on that list until 2008, when it was removed by the George W. Bush administration. But Trump put Pyongyang back on it in November , making the Warmbiers' lawsuit possible.

Theirs is not the first lawsuit against North Korea. Several U.S. citizens sued in the 2000s — and won default judgments, after Pyongyang declined to show up to defend the cases.

The brother and son of Kim Dong Shik, a U.S. permanent resident who was abducted in China and disappeared, sued, alleging that North Korea was responsible. The U.S. District Court in D.C. ordered North Korea to pay $330 million.

Relatives of two Americans who were killed in a 1972 terrorist attack in Tel Aviv sued North Korea for providing material support to the terrorist group behind the attack. The U.S. District Court for Puerto Rico awarded a judgment of $378 million.

Thirty American citizens injured in or affected by a Hezbollah strike in northern Israel sued North Korea and other entities over the attack, receiving a total judgment for some $169 million.

Crew members of the USS Pueblo and their families sued North Korea over the 1968 torture of the crew, receiving a $65 million judgment.

Of course, getting a judgment is one thing. Getting money is another. Federal courts would have the right to seize North Korean assets to pay the judgments — if there were any North Korean assets on U.S. soil not already frozen.

The crew members of the Pueblo never managed to collect their money from Pyongyang, but they ultimately received $9 million from the U.S. Victims of State-Sponsored Terrorism fund. The relatives of the victims in Tel Aviv have attempted to collect that money by seizing North Korean assets related to the registration of Internet domains; so far, that has been unsuccessful.

As for the family of Kim Dong Shik, the last entry in that case's court docket is an attempt to mail a notice of default judgment to North Korea.

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