In a surprise move, Saturday, the United Nations approved new sanctions on North Korea.

As a result, the regime of Kim Jong Un will be banned from exporting any goods or services. The BBC estimates that the sanctions will reduce North Korean exports from $3 billion to $2 billion annually. That $2 billion will be retained by continued illicit trading with nations such as China.

Still, these sanctions are a step in the right direction. North Korea's relentless missile tests have now met their first major pushback. This is a big diplomatic win for the Trump administration.

There are two reasons the U.N. finally decided to act.

First, the Trump administration has convinced China that it is serious in threatening to use force against North Korea. As I've explained, China is pathologically opposed to prospective U.S. military action on the Korean Peninsula. It fears such action would destabilize China's southern border with refugees. China also knows that if North Korea escalated in response to limited U.S. strikes, Kim Jong Un would fall from power and a pro-American unified Korea would follow.

In turn, this U.N. vote signifies that China has decided to do something, however symbolic, to increase its pressure on North Korea. Until now, China had done very little to confront its client state. Again, however, China now fears the U.S. is moving closer to military action.

The second reason for U.N. action is that North Korea has completely isolated itself from the international community.

It's an unusual development. In most U.N. Security Council deliberations of the past 10 years, at least those pertaining to security challenges, nations have often disagreed about addressing threats.

When it has come to Iran, for example, China and Russia have been happy to allow the theocracy to assume nuclear power. Similarly, while European nations oppose Iran's ballistic missile program, they're interested in striking business deals. At the margin, these differences have prevented the U.S. from imposing tougher sanctions on Iran.

Yet recognizing Kim's looming capacity to deploy nuclear weapons against Japan, South Korea, and the U.S., the international community has taken a different approach. And unfortunately for North Korea, it doesn't have much business potential to offer the world.

Of course, those stakes are also informed by Kim's character and record. After all, Kim has proven himself an inherently aggressive and perceptibly irrational actor. Whether in attacking South Korean ships, or purging domestic politicians, Kim has made himself as a major threat to world peace. Certainly someone who cannot be trusted with nuclear warhead-carrying intercontinental ballistic missiles.

Ultimately, as I say, these new sanctions are good news. While China will ignore the sanctions and keep buying North Korean exports, Saturday's development gives new momentum to diplomacy.

That said, much more must be done. The next step in more effective diplomacy is a continued build-up of U.S. military forces in the region. Absent that, China will simply ignore these sanctions and keep patting Kim on the head.