The Obama administration remains stridently opposed to using military force to destroy Iran's nuclear installations. This was made clear during a high-level war game at Harvard's Kennedy School of Government earlier this month. At Harvard, former US undersecretary of state Nicholas Burns played Obama and former UN ambassador Dore Gold played Netanyahu. At the end of the game, the US had disavowed its strategic alliance withIsrael because Jerusalem refused to give Washington veto power over its right to attack Iran's nuclear installations. On the other hand, America had failed to get Russia and China to support sanctions and Iran was three months away from the bomb.
The Harvard game came just a few months after the real-world CIA Director Leon Panetta made what was supposed to be a secret visit to Israel and demanded that Israel not attack Iran without US permission.
All of this makes clear that Israel cannot depend on the US to defend it from Iran. Indeed, it makes clear that a breach of relations with the US is unavoidable.