I don't think the Iranians were ever afraid of the spineless one doing anything militarily to stop their nuclear ambitions.
The Iranians have only been concerned about Israeli military action since Dubya left office. This is a well-founded concern since Israel will only act as a last resort (and thus with a sense of desperation) which means the military response will be huge.
Isreal now has to choose between trusting Obama to protect Isreal or protecting themselves.
I sleep better knowing Israel’s on top of their game - unlike us...