Trump made the announcement via Twitter, describing the news as "very exciting".
The U.S. has long demanded the release of Kim Dong-chul, Tony Kim and Kim Hak-song, the three American citizens who were imprisoned on charges of espionage or other anti-state activities against North Korea.
The three had been held for periods ranging between one and two years.
The fate of the three Korean-Americans had been among a number of delicate issues in the run-up to the first-ever meeting of USA and North Korean leaders, which is being planned for late May or early June.
He also disclosed that Pompeo had set the stage for his meeting with Kim Jong Un, including a date and place he did not fully reveal, after a "good meeting" with the North Korean dictator.
"For decades, we have been adversaries", Pompeo said.
Pompeo said he had planned to raise the issue of the American prisoners but said he did not have any commitments for their release. He said, however, that the USA troop presence in South Korea would not be part of initial negotiations with North Korea. "This is not the result of sanctions that have been imposed from outside".
Pompeo made clear that relief for North Korea's regime was not imminent.
Pompeo's trip to Pyongyang was timed with Trump's declaration that the US would withdraw from the Iran nuclear deal.
Hours before Pompeo landed, Trump yanked the U.S. from a nuclear deal with Iran, complicating the prospects of persuading Pyongyang to surrender its atomic arsenal. Beijing is Pyongyang's main ally and trading partner.
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The airline said it didn't have any additional information about what caused the crash or how the driver was doing. While the plane was stopped on the tarmac, a pickup truck ran into the aircraft.No one was hurt by the wreck.
At a historic meeting inside the Demilitarised Zone last month, Kim and South Korean president Moon Jae-in reaffirmed their commitment to a "common goal" of "complete denuclearisation" of the Korean peninsula.
The historic summit between the leaders of North and South Korea has whetted the former's appetite for investments from the USA, according to a South Korean official, as quoted by the Daily Express. Obama argued that Trump's Iran decision "risks losing a deal that accomplishes" what the U.S. is aiming to do with North Korea. He was confirmed and sworn in as secretary of state on April 26 and quickly departed on his first foreign trip to Europe and the Middle East.
Pompeo took office just two weeks ago, but the West Point grad is a former director of the Central Intelligence Agency.
"Maybe now that we're kind of close to the end. the last few steps for him to be released seems to be going a lot slower than the first year, the whole year", said Sol Kim. Tony Kim, who had been living in North Korea with his wife, taught for a time at the Pyongyang University of Science and Technology. This trip was "to put in place a framework for a successful summit", he said.
"We are very grateful for the release of our husband and father, Tony Kim, and the other two American detainees", the Kim family said in a statement. Trump is hoping to now make headway against North Korea's nuclear weapons program.
South Korea hailed the release of the three USA prisoners as a development that would have a "positive effect" on the upcoming summit between Kim and Trump - and also called for the release of six South Korean prisoners to "reinforce reconciliation" efforts. He added that a political resolution of tensions on the Korean Peninsula and denuclearization should proceed in stages, with all sides moving in concert.
In this photo taken between May 7 and 8, 2018 released by Xinhua News Agency, Chinese President Xi Jinping, (R) speaks to North Korean leader Kim Jong Un in Dalian in northeastern China's Liaoning Province.
Detaining US citizens in North Korea gives Pyongyang leverage in possible negotiations with Washington.
"We'll talk about it again today", he said.
Abe called for additional, specific action, a spokesman for South Korea's presidential office said in a Tokyo briefing.