Last month, North Korea went a couple of weeks without launching any missiles or testing nuclear weapons. That short interval was enough to inspire U.S. Secretary of State Rex Tillerson to declare that North Korean leader Kim Jong Un was showing “restraint.” Perhaps, Tillerson concluded, Kim is ready to engage in dialogue. To some extent, he may be right.

To be sure, claims that the North was showing restraint were clearly premature: North Korea has since fired three short-range ballistic missiles from its east coast into the sea on Aug. 26, launched a ballistic missile over northern Japan on Aug. 29 and on Sunday tested its most powerful nuclear bomb yet. Tillerson’s optimism about such a short pause reflects the pressure diplomats face in reassuring allies — and, in Tillerson’s case, his boss, U.S. President Donald Trump — and easing tensions with enemies.

Nonetheless, Tillerson is probably right that North Korea is ready to talk to the United States — but only as one nuclear-weapons state to another. What the country’s leaders are patently not ready for is to meet America’s own requirement: that negotiations are based on the international commitments made in 2005, at the end of the fourth round of the so-called six-party talks.

Chief among those commitments, enshrined in a joint statement released at the end of the talks, is North Korea’s abandonment of “all nuclear weapons and existing nuclear programs.” In exchange, the other five participants in the talks (China, Japan, Russia, South Korea and the U.S.) were supposed to provide North Korea with energy and economic assistance, respect its sovereignty and pursue the normalization of diplomatic relations. The five participants stood by their commitments, but North Korea repudiated its own in 2009.

According to critics, creating the “precondition” that the North stick to its original commitments amounts to a death blow to new talks. And, indeed, the Kim regime has shown no interest in resuming the six-party process, the stated purpose of which is to denuclearize the Korean Peninsula. In its 2013 constitution, North Korea for the first time even referred to itself as a “nuclear state.”

Tillerson rightly refers to a two-track policy toward North Korea. One track is dialogue; the other is pressure, applied through sanctions and other measures aimed at isolating North Korea and convincing its leadership that it has no future with nuclear weapons.

After North Korea’s tests of its new intercontinental ballistic missile in July, Tillerson and the U.S. ambassador to the United Nations, Nikki Haley, focused on the second track, working with other Security Council members to impose the toughest sanctions ever against the North. Those sanctions could erode much of North Korea’s trade with China, the Kim regime’s economic lifeline.

But the U.S. cannot rely excessively on other countries to constrain the North Korean regime, whose pursuit of nuclear weapons is not a symbolic quest. As its ICBM tests show, the goal is to threaten the U.S. explicitly, in order to compel it to reduce its presence in Northeast Asia — and perhaps even reconsider its alliances with Japan and South Korea.

This ambitious goal is not without tacit support in the world: Russia and China have proposed that the U.S. suspend its annual military exercises with the South, in exchange for a freeze of North Korea’s nuclear program. This supposedly fair-minded “freeze-for-freeze” proposal would do more to weaken the U.S.-South Korea alliance than it would to impede North Korea’s development of a deliverable nuclear weapon.

The proposal highlights how difficult it is to mount an international response to the North Korea nuclear issue. Though China agreed to the recent sanctions in the Security Council, there is widespread skepticism about whether there is an internal consensus about the future it wants for the Korean Peninsula. Russia, for its part, seems to be pursuing a foreign policy guided more by spite than national interest.

America’s allies in the region, meanwhile, are under serious pressure. South Korea’s new government is stuck between the need to manage its relations with the U.S. and the desire to open a dialogue with the North. And, as the North’s latest missile launch shows, Japan’s hosting of U.S. military assets puts it on the front lines of the crisis.

This complex situation would require careful and precise diplomacy in the best of times, with the U.S. using the various levers of its power. But this is not the best of times. Trump has been mercurial, given to making unscripted pronouncements on the topic. This has called for assurances from Tillerson, Secretary of Defense James Mattis and others eager to mitigate the impact of bellicose exclamations — incongruously issued off the cuff from the clubhouse of a golf course — about “fire and fury.”

Trump’s statements about China’s role in addressing the problem don’t help, as they imply an interest in effectively outsourcing the job of reining in the Kim regime, in exchange for vague economic and trade assurances. The result is a perception of American unseriousness about this most serious of challenges.

The Trump administration has assembled before it all the components of an effective North Korea strategy: cooperation with China; pressure on North Korea through sanctions and isolation; reassurance of allies, including by providing the most up-to-date anti-ballistic missile defenses; and a willingness to talk. But for any of these instruments to have an impact, they must be used in concert and with precision in tone and substance — a quality of statecraft that the Trump administration has been slow to master.

In this sense, the challenge in North Korea is not just a nuclear crisis. It is a crisis of the quality of U.S. leadership. Many see the problem, but no one knows yet how to overcome it.

Christopher R. Hill, a former U.S. assistant secretary of state for East Asia, is dean of the Korbel School of International Studies, University of Denver. ©Project Syndicate, 2017