In context, Ahmadinejad's chest-thumping is not a declaration of war; it is not even primarily about Israel. Instead, it is an attempt to bolster, and perhaps even save, his position. It is also part of a wider context for the Islamic Republic --- facing isolation because of the turns in the "Arab Spring" and the crisis in Syria, it is trying to score points with populations in Middle East countries and offer a way back for links with Arab countries, even supposed foes like Saudi Arabia.
It is the nature of politics and media, however, that context gets stripped away. And when that happens day after day, there is the prospect that those in power forget the original purpose of their rhetoric and convert it into reality. That, rather than any immediate cause for a showdown, is the opening for a conflict which moves from words to airstrikes.