In an open letter to Kim Jong Un, Trump said the long-planned summit will not take place, due to a high-ranking North Korean minister’s comments about Vice President Mike Pence.

“I was very much looking forward to being there with you,” wrote Trump. “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. 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.”

Trump promptly followed the cancellation with a veiled threat to the country, adding, “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.”

North Korean Vice Minister of Foreign Affairs Choe Son Hui slammed Pence Thursday, calling him a “political dummy” and saying “as a person involved in the U.S. affairs, I cannot suppress my surprise at such ignorant and stupid remarks gushing out from the mouth of the U.S. vice president”. Those remarks followed Pence’s comments on Fox News saying North Korea could end up like Libya if Kim Jong Un didn’t agree to a deal.

Trump, in his letter, thanked Kim Jong Un for the recent release of U.S. hostages, saying it was a “beautiful gesture” and left the door open for the possibility of another summit at some point in the future.

“If you change your mind having to do with this most important summit, please do not hesitate to call me or write,” he wrote.