CIA Director Mike Pompeo raised the plight of three U.S. citizens held in North Korea during his meeting earlier this month with Kim Jong Un.

That's according to a senior White House official who was not authorized to publicly discuss the sensitive discussions and spoke to The Associated Press on condition of anonymity.

The president on Wednesday confirmed in an early morning tweet that his pick for secretary of state had met with North Korean dictator Kim Jong Un in a meeting that went "very smoothly." Mr. Trump tweeted that the two were able to form a "good relationship" in the process ahead of expected talks between the U.S. and the North.

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A White House official tells CBS News the meeting took place over Easter weekend.

At a press conference Wednesday with Japanese Prime Minister Shinzo Abe, President Donald Trump said the U.S. and North Korea are negotiating for their release. He says: "We are doing our very best."

The official says Mr. Trump is hopeful they will be released soon. Mr. Trump had said he thinks "there's a good chance of doing it" around his potential talks with Kim.

Mr. Trump is also pledging to push Kim to free Japanese abductees held in North Korea.