Emerging from their summit in Singapore, President Donald Trump and North Korean leader Kim Jong Un proclaimed that they had reached an historic deal to denuclearize the Korean peninsula. But while the details of the nuclear agreement would be left to future talks, Trump immediately agreed to end military exercises with South Korea.

“We’re ready to write a new chapter between our nations,” Trump said after their meeting, and added that he had already developed “a very special relationship” with the young dictator from the Hermit Kingdom. He vowed that the removal and destruction of the north’s nuclear arsenal would proceed “as fast as it can mechanically and physically be done,” with complete guarantees of verification. Although he sounded a boastful note about his negotiating prowess, it was not clear what Kim had promised to do or how the United States would be able to ensure that any promises are actually fulfilled.

Indeed, the only firm shift in policy that resulted from the meeting was the abrupt end of joint military exercises that have long irritated Pyongyang — without any notice to either US military leaders in the region or to the U.S. ally in South Korea. Analysts worried that Trump had surrendered the most critical means of leverage to ensure that North Korea actually gives up its nuclear weapons, on the basis of a smile and a vague promise.

Trump held aloft the agreement that the two leaders signed in a gesture of triumph, but its text was not immediately released to the press.