At the end of a shaky week on the domestic front, Barack Obama's shrewd video message to the Iranian people serves as an exciting reminder of this president's foreign-policy potential. Even Tehran's brutal regime can't ignore public opinion at home, and Obama's ability to influence opinion abroad is a powerful new weapon in America's post-Bush diplomatic arsenal. (Consider how absurd Bush would sound issuing the three-minute video's closing line, "Thank you, and Eid-eh Shoma Mobarak.") Obama's critics may deride his popularity as based on nice speeches. But just as those nice speeches overpowered Hillary Clinton and John McCain, and they hold the real potential of outfoxing Iran's leaders.

To be sure, this holiday greeting speech may not dent public opinion in Iran. (It's not as though Iranians haven't been listening to Obama for months already, and today's message said nothing new of substance.) But Obama has another audience here: an international one. If and when the time comes when he finds himself seeking harsh new sanctions--and conceivably even support for military action--against Iran to halt its nuclear program, America will have far more leverage if Obama can say that he made good-faith efforts at dialogue and was rebuffed. Thus, every gesture like today's gives the U.S. more credibility around the world, and puts the Iranians on the defensive if they don't reciprocate. Which may be why Tehran is responding in such a muddled and uncertain fashion.    

--Michael Crowley