How we will trigger WWIII by refusing to fire a shot

The Obama admin is making a huge mistake in refusing to strike Iran's nuclear facilities in a limited conventional fashion. By refusing to do so ourselves with our conventional bunker busting weapons capabilities, we are forcing Israel to do so. And unfortunately Israel does not have the long range conventional capability to do so without sending it's pilots on a one-way suicide mission. Which forces Israel to contemplate Nuclear Weapons in order to get the job done. The political fallout (not to mention the nuclear fallout) that will result from an Israeli nuclear attack on Iran will probably result in an all-out war on Israel from all sides, one in which Israel's survival may well be in question. (At least not without the use of more nuclear arms on the combatants.) Do we really want to be the cause of WWIII?