The friendly relationship between the dictatorial regimes in Iran and Venezuela has long troubled the United States, but the latest expression of this bizarre alliance has implications for Washington’s efforts to isolate Tehran. Iranian President Mahmoud Ahmadinejad is in Caracas this week for another love fest with Venezuela’s Hugo Chavez. The highlight of their exchange was when Chavez referred to a grassy knoll in front of his palace. “That hill will open up and a big atomic bomb will come out,” said Chavez as the two authoritarians laughed about the big joke.

Iran’s nuclear ambitions are no laughing matter for those who fear the Islamist regime being able to put a nuclear umbrella over its terrorist allies Hezbollah and Hamas or being able to threaten Israel with extinction. But the importance of Chavez to Iran is not his ability to provide them with moral support. The only real lever short of the use of force for the West to stop Iran’s nuclear program is an oil embargo. This week’s visit to South America is a reminder that Tehran has allies, including oil producers like Venezuela who may be willing to help them in the event President Obama finds the will to try to enforce a tough sanctions policy.

Ahmadinejad will also be visiting Cuba, Nicaragua and Ecuador, but Venezuela is the key to Iran’s effort to find friends in the Western Hemisphere. Along with friendly nations like Turkey, Venezuela can help Iran evade Western sanctions and may exercise enough economic muscle to ameliorate the effects of an embargo.

But the one piece of good news for the West is the absence of Brazil from Ahmadinejad’s itinerary. The Holocaust-denying Iranian got a good reception there during his last trip to the continent, and the failure of the Iranians to secure another visit may reflect a limited diplomatic victory for the United States. It may also show that for all of its usual willingness to jeer at Washington, Brazil has no appetite for a confrontation, especially with Iran threatening to close the Strait of Hormuz and shut off all oil exports from the Persian Gulf.

This should be a signal to President Obama that, Venezuelan jokes notwithstanding, he will be backed, or at least not actively opposed, by much of the Third World should he decide to impose an oil embargo on Iran. The Iranians are counting on their ability to make friends abroad and Obama’s demonstrated predilection for delay to give them another year or two to complete their nuclear plans. With Iran already enriching uranium in its new mountain bunker at Fordow, time is running out for the West to act.