The only 3 scenarios I can think of:

1. Some other country or countries told him and he wants them to NOT do it so he spills the beans on X.
2. His intelligence services spied on another country and he wants them to NOT do it so he spills the beans on X.
3. Russia is considering to deliver nukes to Iran and he tries to diffuse the source

**Edit:** or a combination of the above. Someone said they'd do it, he picks up on it with hard intel, publishes so they don't, and then Russia does it. Would be great cover because they have the intel to prove that "it wasn't us".

I'm still thinking the most likely is #3 here, but the other 2 are plausible. Russian politicians are well versed at multiple layers of deception.

optimism

Politics_And_Law

Medvedev: Countries Ready To Supply Iran With Nukes

Gotcha. He might plausibly have information about what other countries are planning to do though.