China's foot-dragging on getting tough with North Korea and Iran at the U.N. Security Council has been giving the United States and others fits recently - and for good reason.

Beijing's unwillingness (and Moscow's) to tag either country with economic sanctions under U.N. Charter Chapter 7 has only served to spur on Tehran and Pyongyang's outlaw behavior. (Saturday's U.N. vote on North Korea's missile launches is a positive step, but it only bars missile-related trade - a concession to Beijing to prevent its veto of the resolution.)

In fact, if the United Nations had already taken a muscular stance with both parties, we likely wouldn't be facing Iran's current adventurism in Lebanon or Pyongyang's continued saber rattling.

Be that as it may, Beijing is playing a prominent role in dealing with both, making it a good time to take a look at what informs and motivates Chinese international behavior.

In theory, China's foreign policy is still based on the guidance of former leader Deng Xiaoping (d. 1997), who gave direction in his famous "28-Character Strategy" of the early 1990s: "Observe calmly; secure our position; cope with affairs calmly; hide our capabilities and bide our time; be good at maintaining a low profile; never claim leadership; and make some contribution."

Of course, debate occurs among Chinese elites about the strategy, which suggests downplaying China's ambitions and capabilities in the short term to maximize its long-run options. It's clear that some other imperatives also drive Beijing's thinking.

Nationalism: The belief that the nation suffered 150 years of humiliation at the hands of "foreign devils" (western colonialists and Japanese imperialists) animates Chinese foreign policy. In Beijing's view, it's time to wipe away this disgraceful period of history by returning China to its rightful place atop the international pecking order as the historic "Middle Kingdom."

China already sees its ascension as a certainty, and demands the respect and courtesies afforded a great power - meaning it won't be "bullied" at the United Nations on weighty issues like Iran or North Korea.

Development: Beijing realizes that economic progress is vital to getting to the top of the world political order.

Having seen the Soviet Union, for all its political and military power, land in the dustbin of history, dragged down by economic weakness, Beijing vowed not to make that mistake - and committed itself to a grand strategy that makes economic development a priority.

Today, China is the world's fourth largest economy, having grown at near double-digit rates for a decade - and it holds the world's second-largest foreign currency reserves, too, including our greenbacks.

And that economic strength is translating to political and military power, as planned - yielding kowtows from world leaders and captains of industry alike, and fueling a troubling military build-up as well.

In recent years, Beijing has identified access to energy resources as vital to its drive to secure rapid economic growth. The priority now dominates Chinese foreign policy.

Thus, the unwillingness to punish Iran over its nuclear program stems from Beijing's understanding that U.N. economic sanctions would cut the flow of Iranian oil to Chinese factories. China now gets 15 percent of its oil from Iran, its No. 2 supplier, and will buy $100 billion in Iranian liquid natural gas over the next 25 years.

Security: Instability is bad for economic growth, so China's grand strategy requires tranquility from the 14 nations that ring its periphery. This includes getting along with regional big boys like Russia and India. Plus avoiding a knockdown, drag-out fight with the United States - at present the biggest obstacle to Beijing's global preeminence.

It accounts for China's stubbornness over North Korea, too. Slapping broad sanctions on Pyongyang could cause the rickety regime to crumble, leading to war or refugee flows into China.

And it gives Beijing another reason to cuddle up to Tehran - to ensure the mullahs don't export their brand of Islamic radicalism to China's western province of Xinjiang, home to 55 million restive Muslims.

Bottom line? China's rise may be "peaceful and harmonious," as Beijing asserts. But its ambitions far exceed its historical sphere of influence. Aspiring to replace the United States as the lone superpower, it will inevitably use its growing global influence to balance - if not thwart - U.S. interests whenever necessary.

Peter Brookes, a senior fellow at The Heritage Foundation, is the author of "A Devil's Triangle: Terrorism, WMD and Rogue States."