Nuclear Exchange between Iran and Israel

[TinCow]

That is unlikely as the military bonds present during the Cold War are much weaker now. This is also an exchange that would occur over a matter of days or hours; far too little time for NATO to mobalize. Pakistan wouldn't get involved directly as they lack a sufficient delivery system. China would have the same problem with its army. They would also have to re-nuke portions of tiny Israel.

You're missing the point that such an Iranian-Israeli war would likely exacerbate religious tensions to the point where it would re-ignite the Pakistan-India conflict. That's where their involvement (and possibly China's) comes into play. NATO nations would likely be forced to intervene if a general regional war broke out to protect their own interests, as an Iranian-Israeli war would be almost guaranteed to shut off the oil supply to the west. Russia could see such a conflict as a distraction to allow them to settle some unfinished business in the Caucasus region, most notably with Georgia and Chechnya.