Video Related To: Netanyahu is ready to take responsibility of attack on Iran

Defense Secretary Leon Panetta has a lot on his mind these days, from cutting the defense budget to managing the drawdown of US forces in Afghanistan. But his biggest worry is the growing possibility that Israel will attack Iran over the next few months. Panetta believes there is a strong likelihood that Israel will strike Iran in April, May or June — before Iran enters what Israelis described as a "zone of immunity" to commence building a nuclear bomb. Very soon, the Israelis fear, the Iranians will have stored enough enriched uranium in deep underground facilities to make a weapon — and only the United States could then stop them militarily. Israeli Prime Minister Benjamin Netanyahu doesn't want to leave the fate of Israel dependent on American action, which would be triggered by intelligence that Iran is building a bomb, which it hasn't done yet. Israeli Defense Minister Ehud Barak may have signaled the prospect of an Israeli attack soon when he asked last month to postpone a planned US-Israel military exercise that would culminate in a live-fire phase in May. Barak apologized that Israel couldn't devote the resources to the annual exercise this spring.