Iran's continuing nuclear proliferation is a huge destabilising factor in the region. Going to war would boost Americas economy and push the debt bucket down the road for a while. By eliminating Iran, or bringing it to its knees a huge chunk of the middle east is gone from Muslim power. America would then almost fully surround Pakistan, with India on the other side. Pakistan is now surrounded and its influence is weakened, they stop funding Americas enemies and some stability can be seen to exist in the middle east, but under western influence. Except for a rouge nation here and there, "the west" now stretches uninterrupted all the way from Europe to Russia and China. Russia and China in tern begin to run out of nation states they can arm against the west, as a secondary offence. America et al can now install a curtain of missile defence and launch systems, pinning in Russia and China, ensuring America can sustain its position as the dominating economy of the world.