Israel starts a conflict with Iran and the US rushes to aid Israel for two reasons: 1. Israeli supporters in the US and 2. Israel would use its nuclear weapons if the conflict did not go its way. The US needs to stop terrorism which requires an Israel/Palestine peace but Israel will start a war which is extremely costly to all.
Law expanding definition of terrorist activity passes first Knesset reading (Haaretz)
from the article: Live on Haaretz: Netanyahu and Obama meet in Washington over Iran threat