With the meeting of President Trump and Kim Jong-un of North Korea on Tuesday in Singapore, human rights groups are watching for Mr. Trump to bring up North Korea’s widespread crimes against humanity.

Mr. Kim rules with extreme brutality, making his nation among the worst human rights violators in the world.

In North Korea, these crimes “entail extermination, murder, enslavement, torture, imprisonment, rape, forced abortions and other sexual violence, persecution on political, religious, racial and gender grounds, the forcible transfer of populations, the enforced disappearance of persons and the inhumane act of knowingly causing prolonged starvation,” concluded a 2014 United Nations report that examined North Korea.

Here are some of the atrocities that have happened there.

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A network of prison gulags

Many North Koreans live in fear. That is by design, and it is reinforced by the country’s ruthless police state.

People accused of political crimes are arrested and sentenced to prison camps without a trial, while their families are often kept in the dark about their whereabouts. Up to 120,000 inmates were in the country’s four major political prisons in 2014 and were subjected to gruesome conditions, according to the United Nations report.

Prisoners are starved, forced to work, tortured and raped. Reproductive rights are denied through forced abortion and infanticide. Some are executed — sometimes in public. Hundreds of thousands of political prisoners have died in the camps over the past 50 years, the United Nations report found.

In addition to the political camps, North Korea also operates prisons for those accused of ordinary crimes. Some prisons are short-term labor camps. Others hold prisoners who face long-term torture, starvation and suffering.

Mr. Kim’s enemies, and family, have been executed

Since Mr. Kim assumed power in 2011, taking over from his father, Kim Jong-il, he has consolidated his power through executions. In the first six years as leader, he has ordered the executions of at least 340 people, according to the Institute for National Security Strategy, a think tank arm of the National Intelligence Service.

In 2016, Kim Yong-jin, the deputy premier for education, was killed in front of a firing squad after showing “disrespectful posture” in a meeting. Hyon Yong-chol, a general over the armed forces, fell asleep in a meeting. He was executed with an antiaircraft gun.

Family is also not off limits. One of Mr. Kim’s uncles, Jang Song-thaek, was convicted of treason. He was then executed with antiaircraft machine guns, and his body incinerated with flamethrowers.

Kim Jong-nam, the estranged brother of the North Korean leader, was killed last year in a very public way: near a check-in counter at Kuala Lumpur International Airport in Malaysia. Two women were seen on security cameras walking up to him and rubbing a substance on his face — a chemical warfare agent known as VX, the United States later determined.

Kim Jong-nam was dead within minutes. The women were arrested, but the United States said evidence showed that North Korea was responsible for the attack.