US President Donald Trump’s surprisingly restrained reaction to North Korea’s latest ballistic missile test has left many observers wondering what his next move will be. Trump has publicly declared that North Korea’s goal of developing a nuclear-capable missile that can reach the United States "won’t happen.” But what, specifically, will he do to prevent it?

Some might advise the Trump administration to launch pre-emptive strikes on North Korea’s nuclear facilities. But this is a dangerous and ineffective option, because North Korea would then likely retaliate against South Korea. South Koreans do not want to risk a war, so a US-provoked attack by North Korea would be catastrophic for the US-South Korean alliance.

Moreover, North Korea recently developed missiles with solid-fuel engines, which can be stowed away until just before they are launched, making it technically difficult to identify the right targets – and the right times to strike them.

Another possible response to the North Korean threat is tougher international sanctions, including secondary boycotts. But sanctions that are strong enough to make North Korea’s "Young General,” Kim Jong-un, think twice about his latest provocations will require China’s cooperation, and securing it will not be easy.

Chinese leaders might interpret overly aggressive secondary boycotts as being aimed not only at North Korea, but at China, too. And with the Communist Party of China’s 19th National Congress looming later this year, President Xi Jinping will not want to be perceived as giving in to US pressure.

We know from more than two decades of nuclear diplomacy with North Korea that, to achieve a positive outcome, the Trump administration will have to resolve two fundamental dilemmas. And while past political leaders have preferred to sweep them under the carpet, Trump’s unique, untraditional leadership and negotiating style could enable him to make progress where his predecessors did not.

The first dilemma concerns China. Any diplomatic effort to denuclearize North Korea must also alleviate China’s geostrategic concerns about the future of the Korean Peninsula. For centuries, China has feared that the peninsula could become part of a chain of encirclement, or serve as an invasion route. In 1592, the Japanese general Toyotomi Hideyoshi invaded the Korean Kingdom to establish a beachhead for invading China. In response, China, under the Ming Dynasty, fought alongside Korea against the Japanese army.

Three centuries later, China’s Qing Dynasty fought the Sino-Japanese War of 1894 to prevent Japan from dominating Korea. And again, in the winter of 1950-1951, Chinese Communist Party Chairman Mao Zedong intervened in the Korean War when the US army crossed the 38th parallel and advanced toward China’s border.

China’s current leaders share their forbears’ strategic concern about the Korean Peninsula, which explains their unwillingness to meet fully US demands for action against North Korea. China simply does not want to run the risk of its North Korean buffer state imploding as a result of sanctions. And, because they understand China’s strategic imperative, North Korea’s leaders have felt free to develop their country’s nuclear program.

Trump and Xi have had their first phone conversation, and may soon meet in person. My hope is that Trump will live up to his reputation for boldness, and propose a grand bargain with China that alleviates its geostrategic worries about the Korean Peninsula.

Unless the North Korea problem is separated from the strategic competition between the US and China, diplomatic efforts will continue to fail. So, Trump could promise China that his administration will not seek regime change in North Korea, and instead offer security guarantees if North Korea denuclearizes. Alternatively, he could offer to withdraw the US’s new THAAD (Terminal High Altitude Area Defense) anti-missile system – to which China has objected – from South Korea as soon as North Korea scraps its nuclear program.

Trump could then demand that, in exchange, China cooperate wholeheartedly on sanctions and other efforts to persuade North Korea to abandon its nuclear ambitions. With such a deal in place, China’s existing proposal – denuclearization alongside a peace treaty to bring a formal end to the Korean War – would become achievable.

But assuaging China’s strategic concerns brings us to the second dilemma at the heart of the current impasse: North Korea’s own security. In the brutal world of international relations, a small, weak, and isolated country like North Korea can feel threatened by its neighbors even when they mean it no harm. To compensate for its perceived vulnerability, it strengthens its military and acquires powerful deterrents such as nuclear weapons. But this becomes a vicious cycle, because its neighbors interpret its actions as a provocation, and start to feel threatened themselves.

Former US President Bill Clinton acknowledged this problem and tried to address it. Under the 1994 Geneva Agreed Framework, the Clinton administration succeeded in freezing North Korea’s nuclear activities for several years, by promising to improve US-North Korea relations. And although George W. Bush’s administration consigned North Korea to its "Axis of Evil,” it also recognized the North’s security dilemma, and tried to address it through the Six-Party Agreement on September 19, 2005.

Critics of this approach think that the US has bought the same horse twice, and should focus on sanctions, while waiting for North Korea to make the next move. But sanctions are not effective without robust Chinese support. And North Korea has taken advantage of the diplomatic pause in recent years to develop its nuclear and missile technologies. As a result, we are in a worse place now than when we started.

During his presidential campaign, Trump said he would "have no problem” speaking to Kim. He now has a chance to do just that, by exploring the possibility of a comprehensive deal with North Korea, based on a US security guarantee and economic incentives. But Trump should go down this road only if he is also willing to address China’s strategic concerns. If Trump can strike simultaneous deals with China and North Korea, even his harshest critics will recognize his masterstroke.

The writer is former Minister of Foreign Affairs of the Republic of Korea.