Earlier this month, the national security adviser, John Bolton, said that “The United States has lived up to the Singapore declaration. It’s just North Korea that has not taken the steps we feel are necessary to denuclearize.”

And outside of the Trump administration, many other observers have said “I told you so,” blaming North Korea for that lack of progress while arguing that North Korea will never denuclearize. The Washington Post called North Korea’s hesitation to take action “stiff resistance from a North Korean team practiced in the art of delay and obfuscation.”

Let’s take stock of the concessions by the two sides.

North Korea has imposed a moratorium on missile tests and nuclear tests. It has dismantled entrances to a nuclear test site (at Punggye-ri) and a satellite-launching site (at Sohae). There’s evidence of a shutdown of an I.C.B.M.-assembly facility near Pyongyang. It has returned what it says are the remains of 55 United States soldiers killed during the Korean War and has released three American citizens arrested in North Korea as a condition for the summit meeting. Pyongyang has also reduced domestic anti-American propaganda.

The United States has canceled one war game.

All of North Korea’s concessions were unthinkable less than a year ago. It’s clear that Pyongyang is willing to move toward reducing tensions. A United States commander in South Korea, Gen. Vincent Brooks, noted recently that the North has gone more than 200 days “without a provocation,” and that he had seen a slowdown in the operating tempo of North Korean armed forces.

But further North Korean concessions will not happen until the United States makes a move.

North Korea has never offered to unilaterally disarm first, with the hope that the United States would then do something nice in return. Rather, North Korea has consistently called for a “phased” and “synchronous” approach, with “step for step” negotiations.