Cold War
The Soviet leadership's greatest fear was a re-armed and re-emergent Germany, especially as there were justified concersn that (W) Germany wanted to acquire a nuclear capability. A fear, by the way, that was shared in London and Paris, for similar reasons to those in power in the Kremlin. See Trachtenberg 'A Constructed Peace' 1999 or John Gaddis 'We Now Know' 1997.
But, back to the thread. The Iraqi project, for this has been planned for many years, is best outlined in the recently-published 'America Alone' by Stefan Halper, a former Whitehouse insider. Iran is definitely not the flavour of the month...