U.S. President Donald Trump speaks as he hosts a joint press conference with Japan's Prime Minister Shinzo Abe (not pictured) at Trump's Mar-a-Lago estate in Palm Beach, Florida, U.S., April 18, 2018. REUTERS/Joe Skipper

PALM BEACH, Fla. (Reuters) - President Donald Trump said on Wednesday that negotiations were under way for the release of three Americans held as prisoners in North Korea.

Speaking at a joint news conference with Japanese Prime Minister Shinzo Abe, Trump said: “We are likewise fighting very diligently to get the three American citizens back. I think there’s a good chance of doing it. We’re having very good dialogue.”

A senior administration official said CIA Director Mike Pompeo, who visited Pyongyang secretly in recent weeks, brought up the case of the three prisoners in his talks with North Korean leader Kim Jong Un, and the United States was hopeful for their release.

Trump also said he hoped a planned meeting with Kim to discuss denuclearization would be successful but that he would walk out if it was not.

“If we don’t think it’s going to be successful ... we won’t have it,” Trump said, adding: “If the meeting, when I’m there is not fruitful, I will respectfully leave the meeting.”

Trump, who was hosting Abe and his wife at his Mar-a-Lago resort in Florida, said a campaign of maximum pressure on North Korea would continue until Pyongyang agreed to give up its nuclear weapons.

“There’s a bright path available to North Korea when it achieves denuclearization in a complete and verifiable and irreversible way. It will be a great day for them. It will be a great day for the world,” he said.