The new sanctions that China has reportedly agreed to impose on North Korea are truly a “major upgrade” to existing penalties, as American diplomats say. To make sure they are ultimately effective, however, it’s important to appreciate their limitations.

Under the terms of a Security Council resolution expected to be approved this week, countries will have to inspect any cargo going into or coming out of North Korea. Sales of conventional weapons and aviation fuel to the North will be prohibited, along with its exports of gold, titanium and rare earth minerals. More than 30 new people and entities will be added to a U.N. blacklist for travel and trade.

It’s promising that China has agreed to the tough resolution despite recent friction with the U.S. and its allies. As North Korea’s main trading partner -- accounting for nearly 80 percent of its imports and exports -- China will be critical to making the new measures bite. In recent weeks, some encouraging but unconfirmed reports have suggested that the Chinese may already be tightening up on cross-border trade.

That said, Chinese enforcement of previous resolutions has been inconsistent. The new sanctions reportedly allow North Korea to continue selling coal and iron ore -- its two top exports -- as long as the profits aren’t used for illicit weapons programs. And both the North Koreans and Chinese traders have become expert at conducting business outside of traditional financial channels.

Even if this time the Chinese do put extraordinary pressure on their ally, the sanctions cannot be expected to force all the changes the world wants to see in Pyongyang. They will not bring down the regime and will not dissuade Leader Kim Jong Un from pursuing his ultimate goal -- a working, nuclear-tipped ballistic missile that can reach the U.S. They’re also unlikely to lure the North back into six-party talks to denuclearize the Korean Peninsula.

What the sanctions can do is slow the North’s nuclear and missile programs and reinforce international resolve to block Kim’s ambitions. To the latter end, it is worth pursuing South Korea’s proposed “five-party” talks, without North Korea, to work through differences and show a united front to Pyongyang.

Meanwhile, it seems clear that China’s new cooperativeness is driven in part by a desire to prevent the deployment of U.S. anti-missile defenses in South Korea. Talks on this program should continue, not least to encourage China to fully enforce the new sanctions. The U.S. should encourage coordination with Japan so that the allies’ respective missile defenses reinforce one another.

The U.S. has additional options. Recently approved legislation mandates sanctions against companies that aid the North’s weapons programs. The U.S. Treasury could do more to trace and isolate banks that the regime uses to pay its suppliers. And the U.S. could work to persuade some of its Middle Eastern allies to send home North Korean workers, who remit hundreds of millions of dollars a year.

The North Korean threat will persist as long as the present regime wields absolute power over its isolated citizenry. This is why the U.S. and its allies are right to continue efforts to increase formal and informal efforts to expose North Koreans to life beyond their borders. Such campaigns may take years to bear fruit, but like sanctions, they are essential to eliminating the nuclear danger North Korea poses.

(Bloomberg)