WASHINGTON (Reuters) - U.S. President Donald Trump said on Wednesday the United States is holding negotiations to try to win the release of U.S. hostages held abroad, but he declined to say in what countries.

Trump made the remark at a White House event welcoming Danny Burch, an oil engineer who Trump said last month was reunited with his family after 18 months in captivity in Yemen.

“We have a few negotiations going on right now. I won’t tell you where, because we don’t want to blow the negotiation out the window,” Trump told reporters.

“I love doing it, because I love the end result. This is the end result: a happy man with a happy family.”

The Trump administration has secured the release of a number of U.S. citizens held by other countries for apparent political reasons. Trump himself put the number at 20 during his meeting in the Oval Office with Burch, who thanked the president and senior officials involved in the negotiations.

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A number of U.S. citizens are now held in Iran, Saudi Arabia and Turkey. Most of those freed so far have been from North Korea.

Pyongyang released three Americans ahead of Trump’s Singapore summit with North Korean leader Kim Jong Un last year and freed another detainee later in the year. It obtained the release of American pastor Andrew Brunson from Turkey in October.

The Trump administration secured the release of 22-year-old Otto Warmbier from North Korea in 2017. Warmbier died within days of his return due to an unknown injury he sustained while in custody.

Trump angered the Warmbier family after his Hanoi summit with North Korea’s Kim in late February when he told reporters that Kim said he did not know about Warmbier’s treatment “and I will take him at his word.”

“Kim and his evil regime are responsible for the death of our son Otto,” Fred and Cindy Warmbier said in a statement responding to Trump’s remarks. “Kim and his evil regime are responsible for unimaginable cruelty and inhumanity. No excuses or lavish praise can change that.”