President Donald Trump has canceled his historic summit in Singapore with North Korean leader Kim Jong Un next month.

The meeting, which would have marked the first face-to-face encounter between a sitting U.S. president and a North Korean leader, was set for June 12 in the southeastern Asian island city state.

“Sadly, based on the tremendous anger and open hostility displayed in your most recent statement, I feel it is inappropriate, at this time, to have this long-planned meeting,” Trump wrote in a letter to Kim, which was released Thursday morning.

The news came as North Korea made a show of dismantling a nuclear test site, but also on the heels of some sharp words from the North Korean government about American demands regarding denuclearization.

While much of the letter was written in conciliatory terms, including praise for North Korea’s recent release of three America prisoners, the U.S. president also appeared to issue a threat that conjured memories of his war of words with Kim last year.

“You talk about your nuclear capabilities, but ours are so massive and powerful that I pray to God they will never have to be used,” Trump wrote in the letter.

Read the full text of the letter here:

May 24, 2018

His Excellency
Kim Jong Un
Chairman of the State Affairs Commission of the Democractic People’s Republic of Korea
Pyongyang

Dear Mr. Chairman:

We greatly appreciate your time, patience, and effort with respect to our recent negotiations and discussions relative to a summit long sought by both parties, which was scheduled to take place on June 12 in Singapore. We were informed that the meeting was requested by North Korea, but that to us is totally irrelevant. I was very much looking forward to being there with you. Sadly, based on the tremendous anger and open hostility displayed in your most recent statement, I feel is inappropriate, at this time, to have this long-planned meeting. Therefore, please let this letter serve to represent that the Singapore summit, for the good of both parties, but to the detriment of the world, will not take place. You talk about your nuclear capabilities, but ours are so massive and powerful that i pray to God they will never have to be used.

I felt a wonderful dialogue was building up between you and me, and ultimately it is only that dialogue that matters. Some day, I look very much forward to meeting you. In the meantime, I want to thank you for the release of the hostages who are now home with their families. That was a beautiful gesture and was very much appreciated.

If you change your mind having to do with this most important summit, please do not hesitate to call me or write. The world, and North Korea in particular, has lost a great opportunity for lasting peace and great prosperity and wealth. This missed opportunity is a truly sad moment in history.
Sincerely yours,

Donald J. Trump
President of the United States of America