So why did President Obama opt last week to become the first presi dent since 1991 to not meet the Dalai Lama during his visit to Washington?

Most figure Obama dissed the Dalai Lama in order to curry favor with leaders in Beijing, who view the Tibetan spiritual leader as a separatist and religious troublemaker. And, while Washington has many reasons to try not to grind the gears with Beijing, the one most on-the-boil at the moment is probably Tehran -- where China plays a potentially key role in curbing Iran's nuclear program.

Sure, some are touting "progress" with Iran at the just-concluded Geneva nuclear talks, but we're nowhere near the end of this horror flick. (The North Korean prequel featured lots of "progress," too -- but still finished with a rogue regime having gone nuclear.)

In other words, the United States -- hopefully with lots of partners -- will at some point almost certainly make a last-gasp effort to impose another, more iron-clad sanctions regime to sway Iran from joining the once-exclusive nuclear-weapons club.

Good luck with that one. Hard-hitting sanctions may be the only non-military way left for moving Iran off its nuclear course, but we shouldn't suspend belief expecting it'll be easy -- or successful.

Yet, if sanctions are to have any chance at all, the major powers, including China, must get with the program. No punitive sanctions regime will fly without having Beijing on board, too.

Unfortunately, that'll be a problem: Beijing's into Tehran in a big way.

In addition to being a UN Security Council member with veto rights that give it a big say in a sanctions resolution, China has become a major player in the Middle East. Beijing has no desire to lose that clout by taking any responsibility on the tough calls. (Let the Americans do the heavy lifting, while we enjoy the benefits.)

Of course, China has no interest in seeing the full blossoming of an Iranian nuke program. But, like the Russians, they're probably calculating the Israelis will take it out, so why worry about it?

Plus, as the world's second-largest consumer of energy, China is particularly interested in access to the region's oil and gas, especially Iran's.

Tehran is now Beijing's second-largest oil supplier and largest of natural gas. Chinese firms already have more than $10 billion invested in the Iranian oil/gas sector. (Some estimate it will grow to $100 billion in the coming decades.)

Beijing sees having an unfettered supply of energy as critical to keeping the furnaces of industry burning, and so allowing China to continue its economic growth -- nearly 10 percent a year over the last decade or so.

It's also a political imperative for the Chinese Communist Party, which has an implicit contract with the populace: In exchange for staying in power, it will improve their standard of living.

And as Beijing develops a world-class arms industry, it will also be looking to sustain -- and increase - its export markets, gaining influence with, and profits from, its customer base.

Few countries will sell weapons to Iran, but China has sold some advanced systems, including C-802 anti-ship cruise missiles and patrol boats -- and more may be in the offing.

Worse, there are indications of nuclear and ballistic-missile technology and component transfers, too.

Indeed, some experts believe China will fill any political, economic or military gaps that other powers leave in the Middle East, if doing so can advance Beijing's interests.

What does this mean for Team Obama? It had better have ideas other than sanctions if it wants any expectation of preventing Iran from joining the Mushroom Cloud Club.

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