Looking at the long term goals of Iran any increase (remember they allways keep their western front protected) is not provocation but it is certainly not a defensive thing. The Iranians have been lying about their nuclear program (why the hell does such an oil rich nation need nuclear power?) and the IAEA is doing bugger all about it. If America failed in Iraq it is entirely concievable that Iran would have a "humanitarian intervention" and would sieze the oil fields around Basra, takeover the Central part of the country as well as the Kirkuk oil fields. This would make it the largest oil producer in the world, it would for all intensive purposes be an islamic superpower and it would in all probabilty continue conquesting the ME gaining control of even more.
Luckily if such a situation was to occur Israel is there with its own nuclear weapons and fighter planes and would easily wipe the Insane Mullah's from the face of the earth while the UN quibbles about Irans actions and launches resolutions criticizing the Israel and the USA.