Netanyahu is aggressively trying to persuade President Obama to draw a “red line” on Iran – if Iran crosses the line, presumably drawn on the level of uranium enrichment, they would face a US attack.  Such an attack would set back the Iranian nuclear program but it would likely unify the Iranian population behind the regime and make them redouble their efforts to go nuclear.  So, we should also evaluate what might happen if Iran does go nuclear before we commit to a strategy of a preemptive strike.  It turns out that Jim Fearon thought this through a while ago and did a little empirical work to flesh out the historical record.  He finds:

China, France, India, Israel, Pakistan, and the UK all saw declines in their total militarized dispute involvement in the years after they got nuclear weapons.  A number of these are big declines. USSR/Russia and South Africa have higher rates in their nuclear versus non-nuclear periods, though it should be kept in mind that for the USSR we only have four years in the sample with no nukes, just as the Cold War is starting.

The whole article is an interesting read.