Panetta believes Israel may strike Iran this spring: reports

WASHINGTON (Reuters) - Defense Secretary Leon Panetta believes there is a growing possibility Israel will attack Iran as early as April to stop Tehran from building a nuclear bomb, U.S. media reported on Thursday.

The Washington Post first reported that Panetta was concerned about the increased likelihood Israel would launch an attack over the next few months. CNN said it confirmed the report, citing a senior Obama administration official, who declined to be identified.

"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," Washington Post columnist David Ignatius wrote.

"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," Ignatius wrote.

Ignatius did not cite a source. He was writing from Brussels where Panetta was attending a NATO defense ministers' meeting.

Panetta and the Pentagon both declined comment on the Post report.

Israel, widely believed to possess the Middle East's only nuclear arsenal, views Iran's uranium enrichment projects as a major threat and has not ruled out the use of military force to prevent Tehran from acquiring nuclear weapons.

Iran says its nuclear program is solely for peaceful purposes.

The Post article said the postponement of a joint U.S.-Israeli military exercise that had been scheduled for this spring may have signaled the prospect of an Israeli attack soon.

Washington and the European Union imposed tighter sanctions on Iran in recent weeks in a drive to force Tehran to provide more information on its nuclear program.

Iran has said repeatedly it could close the vital Strait of Hormuz shipping lane if sanctions succeed in preventing it from exporting crude, a move Washington said it would not tolerate.

Israel's military intelligence chief said on Thursday he estimated that Iran could make four atomic bombs by further enriching uranium it had already stockpiled, and could produce its first bomb within a year of deciding to build one.

But in his rare public remarks, Major-General Aviv Kochavi held out the possibility that stronger international sanctions might dissuade Tehran from pursuing a policy he had no doubt was aimed at developing nuclear weapons.

Israeli Defense Minister Ehud Barak said separately that "if sanctions don't achieve the desired goal of stopping (Iran's) military nuclear program, there will be a need to consider taking action."

(Reporting by JoAnne Allen in Washington and Jeffrey Heller in Jerusalem; Editing by Peter Cooney)