A US defence official has predicted that Israel’s retaliation for Iran’s missile attack will be “greater than expected”.

The comments made to Sky News Arabic come amid growing speculation in the USA that Israel may be preparing to hit Iranian nuclear sites.

According to the New York Times, “Pentagon officials have been wondering quietly whether the Israelis are preparing to go it alone, after concluding that they may never again have a moment like this one.”

Iran has more than several dozen nuclear facilities covering the nuclear fuel cycle, from mining to power generation. The two most commonly mentioned in connection with Iran’s not-so-secret weapons program are the nuclear fuel enrichment sites of Natanz and Fordow.

Both are built deep inside mountains, leading some to conclude that even the US, using its largest “bunker buster,” the 30,000-pound Massive Ordnance Penetrator (MOP), could not penetrate them.

But the United States has long tried to hamstring Israel’s ability to take out Iran’s nuclear sites, fearing regional escalation. “President George W Bush turned aside Israel’s demands to give its air force the United States’ biggest bunker-busting bombs, and the B-2 bombers that are needed to to deliver them,” the NYT reported.

Nevertheless, Israel has developed plans to destroy at least Natanz, and “cripple the giant centrifuge hall, where thousands of the tall, silver machines spin at supersonic speeds until the uranium approaches bomb-grade material,” the NYT said.

Israeli Prime Minister Benjamin Netanyahu said hours after Iran’s ballistic missile strike last week, “Iran made a big mistake tonight and will pay for it”.

Israel Defence Forces Chief of Staff Lieutenant General Herzi Halevi promised the IDF would respond with “precise and surprising offensive capabilities”.

Iranian missiles on display in Tehran last month during the 44th anniversary of its eight-year war with Iraq (photo: Getty Images)

America has accepted that Israel will respond to the attack, unlike with the first Iranian missile barrage in April, after which US President Joe Biden advised Netanyahu to “take the win” and not retaliate. Israel limited its response then to a strike on an airbase near Isfahan.

Former President Donald Trump, the Republican presidential nominee, has suggested Israel should “hit the nuclear first and worry about the rest later”.

The Biden administration has offered Israel a “compensation package” if it refrains from striking certain targets in Iran, Israel’s Kan News public broadcaster reported on Sunday, including “extensive diplomatic backing and additional military aid”.

Citing US officials, the NYT report said that a first strike would likely focus on military bases and “perhaps some intelligence or leadership sites”.

However, a US State Department official told CNN on Friday that despite US opposition, Israel has given “no guarantees” regarding its planned attack.

Israel’s Defence Minister is due to meet Defence Secretary Lloyd Austin at the Pentagon on Wednesday.