Well, it won't exactly welch. Because it hasn't exactly promised. And Russia's past behavior when approving sanctions on Iran was first to weaken them ... so that they amount to nothing.
The news appeared in Reuters, reporting that Vladimir Putin has seen nothing to convince him that Iran is on the nuclear arms track. Just when almost everybody else is among the believers, Putin (re)announces his loyalty to the doubters. This is, I suppose, what one expects from Russia.
But does Barack Obama expect this? Or accept it?
Reuters also reported in another dispatch that the White House spokesman, Robert Gibbs, announced that "time is running out" on Iran. This warning has been declared many times by the Obama administration in at least the last eight months. It has been so long that Tehran may have decided to continue to ignore it.
In the meantime, Angela Merkel says she is running out of patience.
The people who are really running out of patience are the Israelis. Beware: They may actually do something.