Could China bring Iran around in a similar way? The two confrontations are different in myriad ways, but there are some signs that the answers could be yes.

White House officials, for example, note that China, which had remained in the background at the United Nations when the United States pressed for more pressure on Iran, has now signed on to two rounds of (mild) sanctions. They say it could support a (tougher) third round if reports expected this fall suggest that Iran is breaking its commitments not to pursue nuclear weapons.

Experts also say China needs Iranian gas and oil for its economic growth — and while this has made it skittish about imposing tough sanctions, it also makes China eager to avert a war in the Persian Gulf that would disrupt energy supplies.

Still, it would be wishful thinking to call China an ally or even a partner, given its historical and political divisions with the United States. China has proved unwilling to go along with much of what the Bush administration has asked of it, especially when it comes to punishing authoritarian regimes. On that score, China’s one-party rulers have always been cautious, calling such measures interference in the internal affairs of others.

Given that history, there are reasons to think that Chinese cooperation on Iran could have its limits. The Korean Peninsula is on China’s border, as is Myanmar, and that alone could explain China’s interest in reducing tensions there. For the United States, fear of Iran’s nuclear capability is linked to fear of Iran’s ties to groups like Hezbollah and Hamas, and to its growing influence in Iraq; those are worries whose urgency the Chinese do not seem to share.