Russian/Iranian nuke deal

I still shake my head wondering what's going through the minds of the Iranian government...

Question on the nuke deal that Russia is offering.

If the Russian's are offering to do the level of enrichment necessary to produce the fuel for a nuclear reactor, aren't the potentially completing the first step necessary for the further enrichment into weapons grade?

What's to say that an Iranians won't take some of the enriched material from Russia and run it through the next process and make weapons? It almost sounds like the Russians are doing them a favor of performing the first step(s).

Not sure if their logic [or even less likely, my interpretation thereof ] is correct, but it could make some sense:

I think the facilities to produce weapons grade material even from reactor grade material are as formidable as those to produce the "first step". If so, then building such a facility would render their intentions obvious. Also, it's a bit easier to monitor the the amounts of nuclear material amassed [they'd only be guessing at the amount actually consumed].

That said, I think the world has gotten crazy enough that the only nuclear anti-proliferation plan that has any chance of working would be "If you show any intentions whatsoever of developing nuclear weapons: nuclear missiles will be aimed at your 10 largest cities with the triggering device unmanned and activated merely by a computer monitoring media to determine if there is better than a 50% chance you are attempting weapons."