Updated May 9.

One was sentenced to 10 years of hard labor in 2016 for an espionage conviction. Two others are scholars — one studies accounting, the other agriculture — who taught at a prestigious science and technology university before they were arrested in 2017 on suspicion of “hostile acts.”

All three are Korean-American men who were held in North Korea until Wednesday, when they were released during a visit by Secretary of State Mike Pompeo to Pyongyang, the North Korean capital.

The three former detainees share a common surname, Kim, but they are not related. Their release removes a point of tension as President Trump and the North Korean leader, Kim Jong-un, prepare for their summit meeting, the first face-to-face encounter by the top leaders of the two nations.

Previous Americans jailed in North Korea have been treated brutally. One of them, Otto F. Warmbier, died in June 2017 after being released from 17 months of captivity. His parents said he had been tortured, and a coroner found that he had suffered extensive brain damage.