China's been building more than an Olympic "one world, one dream" legacy these past few years. According to the Bulletin of Atomic Scientists, the Pentagon estimates China's nuclear weapons inventory has increased by 25 per cent since 2005. It's also developed new delivery systems.

From the Bulletin: (.pdf)

Of the five original nuclear weapon states, China alone is believed to be increasing its nuclear arsenal, boosting its numbers by roughly 25 percent since 2005, according to Pentagon estimates.

Other significant nuclear-related events in China include the deployment of the long-predicted Dong Feng (DF)-31 and DF-31A nuclear-capable ballistic missiles and the Dong Hai (DH)-10 nuclear-capable cruise missile.

Since 1997, the Pentagon has published an annual unclassified assessment of Chinese military power. Its 2008 report concluded,“China has the most active ballistic missile program in the world.” Although the claim is not quantified, the report elaborates that China is “developing and testing offensive missiles, forming additional missile units, qualitatively upgrading certain missile systems, and developing methods to counter ballistic missile defenses.”

Taking these assessments into account, we estimate that China now has approximately 176 deployed warheads, plus an unknown number of stored warheads, for a total stockpile of approximately 240 warheads. Over the coming decade, China is expected to deploy more warheads on new systems but also retire others as it phases out older systems; however, there continues to be substantial uncertainty about the composition of China’s future forces.

Now, it's worth remembering this comes from the United States, the country that brought us the weapons of mass destruction canard in Iraq, so who knows what the truth is. And there is some important qualifying information towards the end:

Estimating the size and composition of the Chinese nuclear stockpile is exceedingly difficult; China does not publicize details about its nuclear forces. U.S. and other intelligence sources release very little information — often contradictory or even exaggerated — about what they know, and unofficial publications and the Internet are awash in inaccurate and unsubstantiated claims.

The article also notes that other nuclear powers aren't standing still:

Faced with U.S., Russian, and Indian nuclear force modernizations, China apparently believes this posture will reduce the vulnerability of its nuclear deterrent.