After years of high-level US pressure on its ally to show restraint, Israel's purported attack on Iran takes the region and Western-led diplomacy into uncharted territory.
Iran and Israel have long waged a shadow war, marked by assassinations of Tehran's nuclear scientists and attacks on Israel by the clerical state's allies in the Arab world such as Lebanon's Hezbollah, but the United States has put a top priority on preventing a wide-scale war.
