As the Trump administration prepares for the June 12 summit on Tuesday with North Korean leader Kim Jong Un, the search for tools that could coax the authoritarian regime to give up the bomb becomes critical.

The White House has given clues over the past weeks that “security assurances” will be at the top of the agenda. But what those assurances are remains vague. President Donald Trump has spoken about his willingness to guarantee Kim’s survival — without defining the terms. He also has dangled the prospect of relaxed sanctions and economic prosperity for nuclear disarmament.

Though Pyongyang has given lip service to the concept of assurances, accepting them would seem to contradict the regime’s longtime mindset of juche, or self-reliance. It must also be mindful of the failure of the past tacit and explicit assurances that Washington respectively gave Libya and Ukraine in return for nuclear elimination.

Though Pyongyang has given lip service to the concept of assurances, accepting them would seem to contradict the regime’s longtime mindset of self-reliance.

The alternatives, however, might well be a greater gamble for North Korea. Kim appears to be looking to end the increasingly stiff international sanctions and the possibility that the United States might initiate war to eliminate his nuclear arsenal — and regime.

This means establishing security assurances that can work is crucial. The peace treaties or non-aggression pacts that some have bandied about make for good photo-ops, but little else. Assurances of a different sort, though, may be relevant here, particularly those that Washington has applied in the past to restrain allies that had the capacity to go nuclear.

At various times, West Germany, South Korea, Japan and Taiwan have contemplated developing nuclear weapons. Yet each never went forward with the plan. They did this because the United States committed to some version of a military alliance and then doubled down on this commitment by putting boots on the ground (or in Taipei's case, ships in the water) to assure the allies’ security and, coincidently, prevent proliferation.

The North Korea challenge requires finding equivalent actions.

Nuclear and conventional trade-offs provide one path. Key components could include: an internationally monitored de-militarized zone with Chinese nuclear inspectors and buffer forces north of the international boundary; constraints on the ability of North Korea, South Korea and Washington to conduct a surprise attack; and reassuring military transparency measures capped by normalized relations between Washington and Pyongyang.

A modest beginning would leverage South and North Korea’s April joint declaration that called for converting the Demilitarized Zone into a peace zone by linking it to a firm commitment from Pyongyang to terminate all its nuclear weapons and missile tests. To enforce the new peace zone, the parties could resurrect or revise the moribund Neutral Nations Supervisory Commission, established under the 1953 Armistice Agreement, to prevent reinforcement of troops and weapons in the region. They could also add several hundred peacekeepers from a mutually agreed list to the current handful of Swiss and Swedish legacy observers, to monitor the exclusion of armed forces from the zone.

The process of nuclear disarmament and confidence-building need not await the zone’s de-militarization. But it might serve to be a confidence-builder because the likely next step of inventorying North Korea’s nuclear enterprise might be the most sensitive. Pyongyang clearly has reason to fear that such an inventory would provide a target list for U.S. defense planners if problems develop in the disarmament process.

Here China, which has had a hollow military alliance with North Korea for decades, could offer the Pyongyang peace of mind by providing various assurance tripwires. Beijing could, for example, contribute inspectors to the International Atomic Energy Agency's on-site nuclear data collection, facility lockdown and dismantlement monitoring. In this way, Beijing would be putting its own personnel in harm’s way to help ensure against any U.S. attack.

China could also make a far bigger contribution — if Pyongyang permitted — with a buffer force of several thousand lightly armed troops north of the de-militarized zone. These would serve as a significant tripwire to ease North Korea’s purported fears about military action from the South.

The process of nuclear disarmament and confidence-building need not await the zone’s de-militarization. But it might serve to be a confidence-builder.

Deployment of such a force could coincide with the dismantlement of Pyongyang’s nuclear infrastructure and could help justify the removal of the Kim’s immense concentration of rockets, artillery and chemical weapons. Because the South Korean capital is only a few dozen miles from its northern neighbor’s military batteries, the dramatic reduction of the South Korea’s defenses is unlikely.

To compensate, Washington could make a symbolic withdrawal of some of the 28,000 U.S. forces currently in South Korea, cut back on military exercises and exclude nuclear-capable B52 bombers from Guam.

Mutual withdrawals and disarmament require verification. Here the International Atomic Energy Agency, bolstered by intelligence from the United States and other nations, will deal with nuclear material. As in many other arms-control agreements, a dispute-resolution panel would help enforce rules.

This layered approach is not without pitfalls. It is likely to face a bumpy road, given the intense mistrust between Washington and Pyongyang.

To reassure that no party conducts secret conventional military increases, and in addition to the Neutral Nations Supervisory Commission playing a role, the United States could provide Pyongyang with a satellite-monitoring platform. The parties could also apply Open Skies, a Cold War program that permitted the over-flight of unarmed sensor-fitted-aircraft across both South and the North Korea.

Fully normalized U.S.-North Korean relations would cap the assurance effort — including the lifting of sanctions. An interim step to ease communication could be interest sections stationed at third-party embassies in both capitals

This layered approach is not without pitfalls. It is likely to face a bumpy road, given the intense mistrust between Washington and Pyongyang. But dire alternatives make it worth the effort. And these layered security assurances offer unprecedented safeguards to assure Kim’s survival without the bomb — while protecting both the United States and South Korea.

Bennett Ramberg served as a policy analyst in the U.S. State Department's Bureau of Politico-Military Affairs in the George H.W. Bush administration. He is the author of three books on international politics.