By dispatching the aircraft carrier USS George Washington to the Yellow Sea to undertake four days of joint military exercises with South Korea beginning Sunday, the US is signaling to North Korea to cease its provocations like Tuesday’s deadly artillery shelling of South Korea's Yeonpyeong island.

It is also letting the people of South Korea know that the US is committed to their defense. “First and foremost, beefing up our military presence and holding these joint exercises … is intended to signal to our allies that we stand behind them,” says Bonnie Glaser, a China expert at the Center for Strategic and International Studies (CSIS) in Washington.

But the naval drills are also a message to China. Washington has been appealing to Beijing for years – under both the Bush and Obama administrations – to do more to pressure its friends in North Korea to stop their belligerent behavior and disregard for international demands, though to little effect.

Now with the escalation that the shelling of Yeonpyeong island represents, the US is signaling to China: You may not like our military presence in your neighborhood, but an increasing American defense of South Korea will be one consequence of a failure to rein in an aggressive and unpredictable North Korea.

“The Pentagon spokesman has been very clear and has emphasized that our dispatching [of the USS Washington] to the region is not in any way aimed at China,” says Ms. Glaser. “But indirectly, I think what we are saying is, if Beijing is unwilling to use its influence to rein in its friends who are behaving in such a negative way, then there will be negative consequences for the Chinese in the region.”

Why China doesn't rein in North Korea

One problem, some China analysts say, is that for all the attention to China’s growing power in its region and the world, it doesn’t have the ability to order around its weak and backward neighbor. And even if it did, they add, China wouldn't want to risk destabilizing North Korea or its regime for fear of losing a useful ally, one which is a buffer against the US military presence in South Korea. A destabilized regime could also prompt hordes of desperate and destitute North Koreans to flee into China.

Related: North Korea's 'military first' politics are behind recent attacks

“China’s unwillingness to put the pressure on North Korea and its leaders means that, unfortunately, China will continue to be a part of the problem rather than the solution,” says Bruce Klingner, a north Asia expert at the Heritage Foundation in Washington. Now is the time, he adds, for Washington to demonstrate to China that its usual preference for accommodating North Korea’s behavior will no longer work in China's interest.

“The US has to make clear that if China refuses to use its leverage, then North Korea will continue to do perhaps even more,” Mr. Klingner says. And if that happens, he adds, “the US and South Korea will be pushed into even stronger responses which are not in China’s self interest.”

Why this time might be different

Still, Klingner says he expects China to respond as it has in the past: by looking to “defuse the problem rather than solving it.” But some factors suggest China could be coaxed to play a more constructive role after this incident, others say.

For one thing, Chinese President Hu Jintao is set to visit Washington in January, “and the Chinese very much want a successful summit,” says CSIS’s Glaser.

But the brazenness of the attack on Yeonpyeong island – and the absence of any doubt about who carried it out – could also prompt the Chinese to take a tougher approach this time.

Glaser notes that Obama was openly frustrated with China’s response to the torpedo sinking in March of the South Korean Navy vessel the Cheonan. China never did agree to explicit international condemnation (through the United Nations Security Council) of North Korea for that attack.

“But we’re in a better position to get a condemnation from the Chinese this time,” she says, “because there simply is no possibility of deniability.”

UN in play

The US is exploring the possibility of seeking a condemnatory statement of North Korea’s action in the Security Council, US officials say. There is some indication, however, that South Korea – wishing to avoid another show of international weakness as after the Cheonan incident – only favors UN action if it delivers a strong statement directly condemning the North.

And while most China experts agree that Beijing can’t simply tell its client-state neighbor what to do, Glaser says that does not mean China has no leverage with North Korea.

“The Chinese don’t control North Korea, but they have a lot of options they can bring to bear,” she says. Those can range from “stern messages” to a slowdown of the assistance North Korea depends on.