By Ian Bremmer and David Gordon

By far the biggest purely geopolitical risk in 2010 comes from Iran. Its government now faces growing pressure on three fronts. At home, the regime has had a tough time since last June's presidential election; hardliners had initially consolidated, but are now under intensifying pressure as domestic protests continue. Regionally, Tehran has lost considerable influence, with elections in Lebanon turning against Hizbullah, rising Iraqi nationalism making it harder for Tehran to exert influence upon their principal historic competitors, and Iran's financial outpost in Dubai put at risk by the growing influence of Abu Dhabi.

Globally, Iran faces a considerably tougher sanctions regime over its nuclear program, a push spearheaded by the United States, Europe, and Japan, with even Russia and China unhappy over Tehran's aggressive rhetoric. A Western push for negotiations will continue, but divisive local politics and insufficient leadership coordination make it very unlikely that Iran's leadership could reach a negotiated settlement even if it wanted one. And it doesn't. Even under considerable domestic pressure, the hardliners in charge of the regime will continue to try to buy time to achieve their nuclear ambitions.

That's why the government is likely to overreact to sanctions when they hit. 2010 carries the highest risk to date of Iranian provocation in the region, in the form of harassment of shipping in and around the Strait of Hormuz, support for radical organizations in neighboring countries, and instigation of trouble for Iraq and other neighbors in demonstrations of muscle. The Iranian regime looks increasingly like a cornered, wounded animal. In 2010, it's likely to act like one.

Israeli military strikes have actually become less likely -- certainly for the first half of the year as sanctions are put in place. Faced with strong opposition from the Obama administration (even as it uses the threat of strikes to gain support for sanctions and to pressure Tehran), mounting intelligence challenges on the location of key Iranian targets, and recognition of the military limitations of Israeli strikes, some Israeli government officials now privately are beginning to discuss how to cope with an eventual nuclear Iran as much as the nature of its "existential threat." Still, the perceived Israeli national security issue is enormous. Looking toward the final months of the year, the Israelis remain an important question mark.

Over time, if the regime in Tehran remains in power, the Iran danger will become more diffuse and start to look more like North Korea. It's clearly a significant long-term negative for global stability. Though for Iran itself, by 2011, we'll probably see a bunch of countries start thinking about how they'd like to start investing there, even as the Western powers seek to prolong sanctions.

Next up: Fiscal issues in Europe

Ian Bremmer is president of Eurasia Group, and David Gordon's is the firm's head of research.