The three key actors in the Korean peninsula crisis are demonstrating why a solution should be anchored in an international coalition and international institutions. North Korea’s Kim Jong-un shows signs ^[1] that he is ready to trade nuclear and ballistic-missile capabilities for security and economic development. US President Donald Trump appears prepared ^[2] to make a deal, but his advisers ^[3] and political party oppose UN sanctions relief. And South Korean President Moon Jae-in has so far been unwilling to articulate and promote a deal that would attract Trump and Kim.

Nevertheless, Seoul is the best-positioned party ^[4] to lead an effort to nail down a new solution. South Korea’s options don’t involve ‘being nice’ to North Korea or ‘going against’ its US ally. Rather, its activism could provide political and optical cover for the US to capture the elusive ‘win’ on Korea that eluded former presidents George W. Bush and Barack Obama. But it can’t do this alone and needs help from other countries and the United Nations.

North and South Korea have each missed opportunities for agreements over the past decades, but the US has had an overwhelming impact. The last time these peninsular and regional opportunities were opening up 25 years ago, the US was leading the way after negotiating the Agreed Framework with North Korea in 1994. It was doing so against strong opposition from the US Republican Party and a conservative South Korean president. The combined scale and expected lasting impact of the agreement and North–South engagement from 1998 to 2000 are rarely remembered now, but they were potentially transformative for the region.

Only two weeks after the Agreed Framework was signed, Republicans had taken control of the US Congress and promptly limited funding for the deal that had stopped North Korean nuclear weapons work. Still, the agreement was only finally abandoned by North Korea in 2003. At that time, North and South Korea, China, Russia and Japan all preferred to keep it in force because the regional changes underway would inevitably accrue to each one’s advantage.

But US unilateral action stopped and reversed those gains. In place of a strategic rationale, officials argued that pressure from sanctions—rather than a path to economic development and security—would force North Korea to surrender its nuclear capabilities. Instead, the US provoked the establishment of the nuclear and missile programs in North Korea that we see today.

The US has taken precisely the same approach to the Joint Comprehensive Plan of Action (JCPOA) between Iran and the P5+1 (China, France, Germany, Russia, the United Kingdom and the United States). As with North Korea, Iran made its agreement before it had any nuclear weapons. As with North Korea, Iran is complying ^[5] with the pact as the US abandons it. Like the Agreed Framework, the JCPOA could not be a treaty because US Republicans would never support it. Finally, as with the framework, the deal being violated by the US is regional in its impacts.

Trump has surrounded himself with a national security adviser, secretary of state and senior ministers who are more ideologically extreme, less bureaucratically capable and less trustworthy than the Bush team that scuttled the Agreed Framework. At the same time, Trump is unschooled in policy or process. He appears ready to make a deal, but also unable to make it happen with the people he has hired.

The history of US opposition to regional nuclear deals with North Korea and Iran, and the link of that opposition to the Republican party’s identity, have devastating implications for South Korea’s interests. Seoul’s tactic of relying on Trump’s personal engagements, expecting him to be able to deliver a realistic deal with North Korea, has shown few results. The aftermath of the third Trump–Kim meeting at the Demilitarised Zone on 30 June has made this clear.

North Korea could have no expectation today that the US would support any relief from UN sanctions under realistic conditions. In the month leading up to the Hanoi meeting, US negotiators made public speeches clearly stating that no UN sanctions relief would be on the table. That followed more than a year in which North Korea repeatedly indicated that such relief would be the most important part of any deal. Both the North Korean and US positions were reaffirmed again ^[6] this month, after the theatrical DMZ meeting.

In this situation, Seoul has the potential to take the lead and spell out and fill the gaps of the deal that was pending in Hanoi and get Kim’s agreement to it. The deal should include shuttering the Yongbyon facility and capping all fissile material production—including full inspections—as well as formulating a road map. Immediate and significant relief from some UN sanctions ^[7] should follow quickly. The argument that the North requires extreme sanctions as an incentive is easily debunked, as is the view that relief from crippling non-strategic economic punishment is ‘too much’ in exchange for significant and meaningful steps towards denuclearisation. Seoul should make that deal public. After that, the task of implementing the deal should rest with the United Nations.

The US would have extensive strategic and political reasons to agree to the deal. Among them is the fact that Trump will have demonstrated that he is a better dealmaker than Bush and Obama. Without this deal, he will have no substantial achievement on North Korea to point to. If the US doesn’t support a deal publicly spelled out by the two Koreas and supporting countries, an international coalition led by Seoul should act to ensure US opposition doesn’t add Hanoi to the 1994 agreement and the JCPOA as one more opportunity for denuclearisation, development and security that was regionally supported but unilaterally blocked by the US.

The UN 1718 Sanctions Committee could vote to suspend key non-strategic sanctions, as proposed by North Korea in Hanoi. As Trump suggested ^[8] at the time, a snap-back provision would provide added incentive for the North. The US could support, abstain from or oppose this vote. The members of the UN would be left to publicly decide whether the current US administration—acting against its domestic, regional and non-proliferation interests—could again prevent the UN from fulfilling its mandate.

Since March of last year the most consequential fight over North Korea has been between Trump on the one hand, and his advisers and party on the other. Seoul may learn that power unused begins to vanish, so it should step forward now. Washington might learn that the only deal that works for Trump politically is one that substantially relieves non-strategic sanctions on North Korea. Such an exchange is the only scenario in which all three get what they need.