Senior Israeli defense officials told The Jerusalem Post this week that they are preparing to launch an aerial assault on Iran's nuclear facilities even without US assent.
America controls most of the airspace between Israel and Iran, so reaching the targets would be difficult without receiving the proper US Air Force codes, though not impossible, according to the Israelis.
Israel believes it must be fully prepared to strike Iran at a moment's notice, as international diplomatic efforts to curb Iran's nuclear program have proved ineffective. A nuclear-armed Iran is an existential threat to the Jewish state, and is viewed by Jerusalem as a totally unacceptable outcome.
According to reports last summer, Prime Minister Ehud Olmert wanted to attack Iran in May, but was denied the green light he sought from US President George W. Bush.
At the time, Israeli leaders consoled themselves that the Bush Administration also viewed an nuclear-armed Iran as a red line, and would never allow the Islamic Republic to build atomic weapons.
But for months Israeli analysts have warned that with US President-elect Barack Obama in the White House, and threat of American military intervention will disappear, as will any possibility of gaining official or even tacit US support for an Israeli strike.