The United Nations imposed significant new sanctions on North Korea last weekend, in response to the dictatorship's repeated ballistic missile tests. Kim Jong Un's regime will be banned from exporting goods and services and cut off from foreign investors, at least to an extent.

This combined effort to confront what is, among other things, the foremost national security threat to the United States, is a big win for President Trump.

Deploying diplomacy backed by the credible use of force, he and his UN Ambassador, Nikki Haley, were able to rally the entire 15-member UN Security Council into concerted action. While these sanctions won't alone bring Kim Jong Un to serious negotiations, they will cause him real pain. Analysts believe the sanctions will cost North Korea around a third of its $3 billion total export market.

While North Korea's transgressions — it's evil, so let's say it plainly — are undeniable, this sanctions vote was far from simple. It required China to change. Beijing would not have done so without believing that Trump might take military action against North Korea. Up until now, China's actions against Kim have been limited. Allowing this vote to pass the United Nations Security Council, where it has a veto, however, demonstrates that when Trump makes a military threat, China takes him seriously.

That is a 180-degree about face from its approach to North Korea over recent decades, reflecting a shift in U.S. policy.

In 1994, the Clinton administration, acting after on the vapid advice and after the grating intervention of former President Jimmy Carter, offered fuel aid to North Korea in return for its promise to suspend nuclear research. The deal lacked safeguards and North Korea immediately began cheating, as sensible people predicted it would.

In May 2009, after North Korea tested a nuclear weapon, Rahm Emanuel, the White House chief of staff, gave a vintage Obama administration response, "I think we were all impressed with the fact that the Russians and the Chinese denounced this so strongly." The Chinese were surely laughing up their sleeves at this absurdity. It would set the tone for the remainder of Obama's years in office.

In 2010, after Kim Jong Un orchestrated the North Korean sinking of a South Korean ship, then-Secretary of State Hillary Clinton pledged to respond with a "clear and unmistakable message". As good as her word, she did nothing — message received and clearly understood.

In January 2016, her successor, John Kerry, tried to persuade China to restrain North Korea's nuclear program. But when asked whether the U.S. would increase its pressure on China if it didn't act, he havered, saying, "It's time for everybody to make sure that this does not continue as business as usual." Predictably, it did.

Shortly before leaving office, the Obama administration passed a U.N. resolution restricting North Korea's coal exports. But unlike Trump's resolution, that one lacked a corollary threat and so China continued dancing with Kim.

Trump's approach has changed everything and shown his ability to do what others have not. Supported by Nikki Haley, Trump has, on China and North Korea at least, strengthened the foundations of American diplomacy. The combination of hard and soft power is important. Authoritarian regimes such as China's are unimpressed if international agreements don't have teeth as well as smiles.

This diplomatic success is also crucial in the precedent it sets. With Iran rapidly advancing its own ballistic missile program, Washington must ensure that hostile adversaries are aware that ballistic missiles offer only existential danger, not security. If North Korea's ballistic missile program is allowed to rise unchallenged, Iran and others will pursue that technology as their first priority. Why wouldn't they? If North Korea gains regime security from the possession of ballistic missiles, other regimes will seek the same safety. The stakes are high, considering Iran's penchant for theologically rooted expansionism and the political sectarianism that defines Middle Eastern politics.

Further action will be needed against North Korea, Iran, and any other actor who follows their path.

First, Rex Tillerson urgently needs to get on the Trump-Haley script and stop presenting a message of American confusion. Second, Trump must continue his military buildup around the Korean Peninsula, which has been instrumental not just in pressing China to corral North Korea, but also in ensuring that American commanders have the means to take decisive action if necessary. Third, in return for supporting the Iran nuclear deal's continuation, Trump must rally U.S. allies to support a crackdown on Iran's ballistic missile program.

In Ukraine, Syria, and the East and South China Seas, Obama's policies persuaded the Chinese that America was weak and would offer only ineffectual opposition to those threatening its interests and security. That has now changed. Cultivating a perception of inherent unpredictability, crafting credible diplomacy, and broadcasting confident military strength, Trump is turning heads in the capital of our long-term strategic rival.