In the summer of 2018, President Trump met with North Korea’s Kim Jong Un in Singapore. It was a historic meeting — Washington and Pyongyang had been at odds over nuclear weapons for decades — and the two men signed a document that set out an ambitious vision for a peaceful future.

“There is no longer a Nuclear Threat from North Korea,” Trump tweeted just one day after the June 12 meeting.

A year and a half later, that optimism is gone. North Korea resumed missile testing in May 2019, and on Sunday it claimed to have conducted a “very important test” at a rocket launch site. It has stated that the end of this year is a hard deadline for negotiations with Washington, warned of an unwelcome “Christmas gift” and resumed using insults to refer to Trump.

Trump, mired in disputes at home and abroad, has largely ignored the subject of North Korea. But on Sunday, he returned to it in a tweet, pointing to the “strong Denuclearization Agreement” in Singapore but warning North Korea could lose “everything” if it acts in a hostile way.

So what went wrong?

A short document, light on specifics

There was a dramatic increase in tension with North Korea during the first year of Trump’s presidency, with the isolated country conducting at least 20 missile tests, including of large-range missiles, and testing a huge new nuclear weapon. In August 2017, Trump said Pyongyang would be “met with fire and fury like the world has never seen” if it continued to threaten the United States.

But tensions cooled in 2018, with North Korea unilaterally announcing it would halt weapons testing. When Trump and Kim met in June, the first time a sitting American leader had met with his North Korean counterpart, they signed a document that set out goals: peace and prosperity, denuclearization, and the resolution of the Korean War.

The event was a huge spectacle, with media converging from around the world. However, the actual impact of the summit in Singapore was hard to gauge. Publicly, the two sides issued only a statement of just over 400 words that touched on four vague issues:

  • A pledge to “establish new U.S.-DPRK relations in accordance with the desire of the peoples of the two countries for peace and prosperity.” DPRK are the initials of North Korea’s official name, the Democratic People’s Republic of Korea.
  • Joint “efforts to build a lasting and stable peace regime on the Korean Peninsula.”
  • A pledge to work “toward complete denuclearization of the Korean Peninsula.”
  • The return of the remains of U.S. service members who were killed during the Korean War.

There was also no promise to stop testing in the document — Kim had made his unilateral pledge to stop testing in April 2018, saying at a meeting of the Central Committee of the ruling Workers’ Party of Korea that North Korea had “verified the completion of nuclear weapons” and would end nuclear tests — and only a vague reference to “denuclearization.”

Failed follow-ups

With the two heads of state setting out only broad aims, working-level meetings were expected to help sort out the details. But time and time again, these meetings were canceled or ended in acrimony, like a meeting in Stockholm in October that North Korea’s Foreign Ministry called “sickening.”

Trump’s personal touch couldn’t bridge the gap. The president met again with Kim, this time in Hanoi, in late February 2019. But the two sides abruptly cut short the two-day summit when they could not agree on what North Korea would give up for sanctions relief. In a news conference afterward, North Korean Vice Foreign Minister Choe Son Hui said the United States was missing a “once-in-a-lifetime opportunity.”

Trump met with Kim for a third time in June, taking a step into North Korea at the demilitarized zone that divides the peninsula. Despite the symbolism, there was little progress on key areas of the dispute. In a blunt statement last month, North Korea pushed back on Trump’s suggestion of another summit. “As we have got nothing in return, we will no longer gift the U.S. president with something he can brag about,” Kim Kye Gwan, a veteran diplomat, said in a statement carried by North Korean state media.

Limited progress

Regarding the goals set out by Trump and Kim in Singapore, a charitable reading would conclude that progress has been limited. North Korea did stop testing and partially destroyed one nuclear test site, but it did that before the summit had even taken place, without international verification, and later resumed short-range missile testing.

The United States has postponed joint military exercises with South Korea but refused to lift the sanctions that North Korea views as key to negotiations. Those restrictions have meant South Korea has limited room to begin the inter-Korean projects at the center of its own rapprochement with Pyongyang.

In late July 2018, the United States received 55 boxes that were said to contain the remains of 55 Americans who were killed during the Korean War. But since then, efforts have stalled: In May, the Pentagon announced it would suspend the operation to recover war remains, as U.S. officials had been unable to reach their counterparts in the search.

Differing motivations

The difference between the two sides boils down to sanctions and nuclear weapons: The United States won’t drop the former without North Korea giving up the latter, but North Korea refuses to give up the latter until it sees some progress on the former. But it’s also not quite that simple.

The United States, for example, appears willing to offer limited sanctions relief to North Korea, but it is hesitant to lift U.N. Security Council sanctions as they cannot be easily put back in place. North Korea has offered to decommission Yongbyon, a major nuclear facility, but U.S. officials have said that is not enough.

For months, both sides let the issue languish. But North Korean state media has recently reiterated it views the end of the year as a deadline for progress on negotiations and has promised a “Christmas gift” — probably a euphemism for some sort of long-range missile test or another weapons test. Some of the change in stance may be because of the considerable economic pressure on North Korea as a result of the sanctions.

But it is also likely Pyongyang is considering the U.S. political timetable. Trump is less than a year away from the presidential election, with few foreign policy successes in his first term. Kim’s own political worries are very different.