It's time to get over the notion that China is going to play a strong, pivotal role in handling its belligerent nuclear neighbor, North Korea.

Beijing is certainly capable of playing tough with Pyongyang, but it seems increasingly unwilling to do so. The sooner we figure this out, the better off we'll be.

For instance, the Chinese didn't prevent either of North Korea's nuclear tests (2006 and 2009). Nor has it stood in the way of any of Pyongyang's long-range missile launches, either.

Considering the two countries' close ties, it's also hard to swallow the notion China didn't know about North Korea's just revealed uranium-enrichment facility. It's certainly turned a blind eye before to the Pyongyang proliferation problem.

Moreover, China was stone quiet on North Korea's sinking of a South Korean warship this spring, refusing to assign blame -- and soon after giving North Korean leader Kim Jong-il the red-carpet treatment in Beijing.

Déjà vu all over again: China was also pretty mum last week when North Korea pushed the peninsula closer to the abyss by shelling a South Korean island -- and yesterday, China again welcomed a North Korean envoy to Beijing.

Reeling in North Korea's bad behavior, which threatens war and leaves the whole region less stable, is certainly in Beijing's interest. So why doesn't it yank Pyongyang's chain when it misbehaves?

First, while the Chinese may see North Korea as a troublesome, even a spoiled country cousin, it's an ally that provides bennies for Beijing. Above all else, it keeps the Korean Peninsula divided; China does not want a powerful Korean neighbor on its northern flank.

Especially not one that continues its alliance with America, meaning US troops might end up on China's border -- an event that triggered Beijing's entry into the Korean War in 1950.

In fact, while the Chinese benefit from the stability the United States has given Asia since World War II, as their power grows relative to others, the less they want to see of America.

Beijing certainly doesn't mind having the nettlesome North distract its rivals in Washington and Tokyo with its provocations -- leaving them less time and resources to focus on China's rise.

Finally, the collapse of North Korea, which might happen if Beijing stops forking over food and energy aid, could trigger a vast flow of refugees into China, or even incite a North Korean civil war that might include a tussle over nukes.

So, even though it benefits Beijing to keep the lid on Pyongyang, its efforts will comport with China's interests -- which may not align with ours.

We're told, "The road to Pyongyang goes through Beijing," but that hasn't often been the case -- and it's wishful thinking to believe we can access the on-ramp. Barring some pleasant surprise, keeping North Korea in line is going to fall mainly to the United States, South Korea and Japan. It won't be easy.

Although no "hard power" fan, President Obama's decision to send an aircraft carrier battle group to the Yellow Sea (between China and North Korea) to exercise with our South Korean allies in a show of power was the right call. It sends a strong signal to both Pyongyang and Beijing and may be the readiest remedy for deterring North Korea's next hostile act. Our naval presence also prods China to rethink North Korea, although we should keep our expectations low.

The only problem is the White House should've laid on the military muscle a long time ago to get North Korea's and China's attention sooner -- nor should it be afraid to do so again in Korea (or elsewhere) to protect US interests.

Peter Brookes is a Heritage Foundation senior fellow and a former deputy assistant secretary of defense.