Washington: A 13,600kg bunker buster bomb designed to smash through some 200 feet of concrete before exploding is a "great weapon" that could be used by US forces in a clash with Iran over its nuclear program, an Air Force general said.

Lieutenant General Herbert Carlisle, Air Force deputy chief of staff for operations, said the massive ordnance penetrator, which the military began receiving only last year, is part of the US arsenal available for strikes against countries like Iran, which has some buried nuclear facilities.

"The massive ordnance penetrator is a great weapon. We are continuing to improve that. It has great capability now and we are continuing to make it better. It is part of our arsenal and it will be a potential if we need it in that kind of scenario," Carlisle told a conference on US defence programs.

The Pentagon has begun working on military options if sanctions and diplomacy fail to prevent Tehran from building a nuclear weapon.

Defense Secretary Leon Panetta told the National Journal in an interview on Thursday that planning had been going on "for a long time."

Major powers are increasingly concerned about Iran's nuclear enrichment program, which they view as an attempt to build an atomic weapon. But Tehran says it is meant for peaceful energy production.

Israel also is worried about potential for Iran to acquire nuclear weapons. Prime Minister Benjamin Netanyahu said during a visit to Washington this week that time was running out for diplomacy and sanctions.

"HELL OF A BIGGER IMPACT"

Panetta, who has said diplomacy and sanctions should be given more time, told the National Journal he did not think Israel had decided whether to order a high-risk raid on Iran's nuclear sites.

He said the United States was committed to preventing Iran from acquiring atomic weapons and would have a greater impact than Israel if it decided force was necessary.

"If they decided to do it there's no question that it would have an impact, but I think it's also clear that if the United States did it we would have a hell of a bigger impact," Panetta said.

The tough rhetoric from the Pentagon came despite President Barack Obama's effort this week to tamp down "loose talk" and "bluster" about possible military action, saying there was still an opportunity for diplomacy.

Carlisle also told the Credit Suisse-McAleese defense conference that a conflict with Syria or Iran could see U.S. military operations influenced by new tactical thinking at the Pentagon known as Air-Sea Battle.

That approach aims to take advantage of highly networked and integrated U.S. forces. Carlisle said the tactics focus on operating in multiple domains, from air and sea to space and cyberspace, while networking and integrating information from the different areas, like satellites and sensors on stealth fighters and unmanned aircraft.
"There's a space capability, there's a cyber capability, there's fifth-generation, low-signature force capability," he said.

"All those things are on the table and being thought about as we do this operational planning," Carlisle added, noting that Syria and Iran have developed significant defenses aimed at keeping potential attackers at a distance, a strategy Air-Sea Battle was designed to circumvent.

Carlisle said cyberspace could be a factor in a conflict with the two countries.
"All of the leadership has said nothing is off the table with respect to what we would employ and use," he said.