President Donald J. Trump detailed his decision to cancel a scheduled meeting with King Jong-un on Thursday, after publicly releasing a letter that he sent to the North Korean dictator.

“Nobody should be anxious,” he said. “We have to get it right.”

The president made his remarks to reporters during the signing ceremony of a Dodd-Frank reform bill at the White House on Thursday afternoon. He called it a “tremendous setback” for North Korea and for the world.

He said that he would continue to be open to the idea of a summit, even one on June 12, but only if denuclearization of the Korean peninsula was on the table.

“If and when Kim Jong-un chooses to engage in constructive dialogue and actions, I am waiting,” Trump said bluntly, adding that the economic sanctions against North Korea would stay in place as well as the campaign as maximum pressure.

He said that the United States military was prepared to defend allies in the region like Japan and South Korea and that they were willing to shoulder the financial burden.

“I hope that Kim Jong-un will ultimately do what is right,” Trump said, saying that the North Korean people deserved peace. “The bright and beautiful future can only happen when the threat of nuclear weapons is removed.”

In the letter to Kim, Trump said that the hostile statements from the regime made it impossible to have the meeting.

“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 the letter.