Syria’s Bashar al-Assad is begging for a trip to Pyongyang as Donald Trump prepares for a summit with Kim Jong-un. Hollywood would reject such a script as outlandish, yet the scenario offers a reminder of the connections among Syria, Iran and North Korea – and some justification for different treatment by the current US administration. The US president expresses hope of signing a denuclearization agreement with North Korea after tearing up the US agreement with Iran, inspiring easy comments on the irrationality of Trump’s foreign policies. Breaking the convergence between the North Korea and Iran may prove essential.

The relationship between Iran and North Korean proliferation is deep and longstanding. The parallel between the two nations is real, with mutual help and cover at critical junctures, along with a converging connection to Syria, and separating the proliferators makes sense. This was true in 2017, when Iran announced resumption of its long-range missile program, a decision publicly floated at the height of the international standoff with North Korea over its missile launches and nuclear tests. During this period, according to a UN report, two North Korean ships delivered crates to Syria’s Scientific Studies and Research Center, the same chemical weapons-research center destroyed by a joint US-France-UK strike in April – a detail adding intriguing context to Assad’s plan to visit Pyongyang.

North Korean–Iranian ties go back to the first Gulf War. In the early 1990s, North Korea considered supplying mid-range ballistic missiles to Syria, creating enough angst in Israel that it sent to Pyongyang an unprecedented exploratory mission. Syria signed a scientific agreement with North Korea, in 2002 undertaking a covert nuclear reactor project provided by North Korea – destroyed by Israel in 2007. Iran signed its own deal with North Korea in 2012; cooperation was apparent before and after the Joint Cooperation Plan of Action was signed in 2015.

The comparison stops there. Iran recovered some financial resources with the 2015 agreement, while North Korea has endured increasingly biting sanctions. Iran is only a threshold nuclear power while North Korea, after decades of efforts starting with Soviet help in 1955, is a nuclear weapon state. Iran is a major regional threat, as the mullahs finance and arm militias in Syria, Lebanon, Iraq and Yemen. Iran, as exposed by Israeli spying and previous International Atomic Energy Agency inspections, was close to the design and supplies for a nuclear weapon. Given North Korea’s proliferation record towards Pakistan and the Middle East, as noted by US Ambassador to the United Nations Nikki Haley, little prevents North Korea from sharing designs for nuclear warheads or selling missile parts. The nation carried out missile sales in the past, repeatedly expecting compensation to stop the practice.

Like a jigsaw puzzle, Iran and North Korea expose gaping holes in nonproliferation policies.

First is the permanent failure to ban development of ballistic capabilities along with nuclear weapons. The Missile Technology Control Regime is a voluntary export regime. No UN resolution on North Korea or Iraq has formally declared testing of ballistic missiles as illegal, though several pushed for a halt. Famously, the Iran agreement did not include such a prohibition. By contrast, North Korea did sign an agreement covering missile launches, then argued that satellite launches were not included. The spectacle of Iran developing more ballistic missiles or a nuclear submarine, when it’s supposed to desist from nuclear weapons, is a farce played on agreement signatories.

The second gap is the time limit, to 2025 and 2030, set by the Iran agreement for high-grade nuclear enrichment. The  agreement may have been the best available, but still a huge can was kicked down the road, reminiscent of the US–North Korea Geneva Agreement of 1994: constructing a civilian nuclear plant in return for North Korea’s agreement to account for its plutonium production and desist from future efforts. The replacement plant was supposed to be built by 2003, with verification of nuclear activities as certified by the IAEA. Chief US negotiator Robert Gallucci is said to have privately noted that the North Korean regime would collapse by 2003. Instead, construction stopped that year with the agreement formally denounced in 2006. By then North Korea had started its nuclear-enrichment program.

Formally, Iran did not demonstrably cheat on the 2015 agreement.  But it has developed a massive ballistic program and presents a regional threat. North Korea is accustomed to cheating yet presents less regional danger, except in preemptive and suicidal self-defense. Still, North Korea tested the submarine-launched ballistic missile and supplied pocket submarines to Iran that could be used against the Ormuz Straits. The design of Iranian and North Korean conventional submarines share commonalities; Iran has the cash to develop nuclear propulsion.

Successful arms-control agreements have started with limitations on missiles, going on to nuclear warheads. For example, to this day, many withdrawn US and Russian warheads remain in storage. Cheating is expected in halfway agreements, whether formal like Pyongyang’s open defiance or in spirit like Iran’s pursuit of ballistic missiles without warheads. Among non-democracies, only Libya abandoned its program without regime change. North Korea’s recent outburst against what it regards as excessive requests emphasizes that Libya was not yet a nuclear power and not rewarded.

By happenstance or design, Trump’s initiatives build on the differences between Iran and North Korea. For Iran, the missile issue is paramount. The allied US-France-UK strikes on Syria and devastating Israeli hits on underground structures deliver the message that Iran’s missile sites could also be hit. Nuclear weapons without missiles are relics, the line apparently taken by US Secretary of State Mike Pompeo whereas National Security Adviser John Bolton demands immediate, complete denuclearization.

Eliminating the missile threat against the United States leaves regional allies exposed. That was also the case with arms-control agreements of the Cold War era – for example, the SS20-Pershing controversy of the 1980s, when Europe and Japan feared exposure. The expanding US nuclear arsenal, including low-yield weapons, could be used as a bargaining chip. Ending North Korea’s nuclear program, as suggested by Pompeo, but not mentioning existing stock goes along with stray promises to refrain from seeking regime change and making North Korea as rich as South Korea.

The current path cross between immediate delivery and down payment, as favored by part of the Trump administration, and the “phased and synchronous denuclearization” pushed by Kim Jong-un and China.

The 2015 Iran agreement addressed fissile materials while a plan for North Korea could start with missile categories. A breakthrough requires a change of behavior. The administration cannot negotiate arms-control deals and push regime change at the same time: Trump professes to abandon the latter, and the North Koreans are correct about the need for security guarantees. Against all expectations, Kim’s propaganda machine is balancing China, while giving huge domestic exposure to developments underway with South Korea, China and the United States.

Trump is likely to disappoint regional allies, especially Japan, by leaving in place shorter-range missiles and perhaps warheads.

Regime change for Iran – through a domestic process – remains a tempting option for the US and regional allies. President Hassan Rouhani does not have complete control. With or without the 2015 agreement, Iran remains bound by IAEA inspections, forced to choose between staying within international law or going rogue. Trump removed most incentives for Iran to comply and must bank on regional allies – Israel, Saudi Arabia, the Gulf States, Egypt – to contain Iran. He must also hope that Europeans, despite anger over US withdrawal, persuade Iran to abide by the agreement.

Withdrawing from a UN-sanctioned agreement is a loss for the international system, since Iran did not demonstrably cheat. Yet Iran used the agreement to expand regional influence and pursue a ballistic race. Overextended Iran must make choices.

So much security depends on US policy staying power. If US policy on Iran stays erratic, or becomes so on North Korea, that will embolden adversaries to a degree not seen before. Europe has few alternatives, and ending the Western alliance would be suicidal. Instead, Europe must rise above political debates and push for steady US policies, demonstrating to Iran that compromise on missiles is required, while liaising with regional Asian partners to ensure that negotiations do not neglect fissile materials.