U.S. President Barack Obama's administration is reportedly considering an urgent request by Israeli Prime Minister Binyamin Netanyahu for GBU-28 bunker buster bombs and tanker aircraft that would be used in any Israeli strike on Iran's nuclear facilities.

The Israeli air force's lack of the systems is widely seen as a major impediment to Netanyahu ordering airstrikes aimed at slowing the Islamic Republic's nuclear program, which Netanyahu sees as an existential threat to his tiny country.

The Israeli request isn't new but the added urgency of Netanyahu's request during his Monday meeting with Obama underlined the do-or-die emphasis the hawkish Israeli leader places on eliminating the Iranian nuclear threat.

The Obama administration secretly supplied Israel with 55 of the 5,000-pound GBU-28s in 2009 but has rebuffed requests for more, apparently for fear it would encourage Israel to act unilaterally against Iran and trigger a regional war.

The Haaretz daily reported Obama has instructed U.S Defense Secretary Leon Panetta "to work directly with (Israeli) Defense Minister Ehud Barak on the matter, indicating the U.S. administration is inclined to look favorably upon the request as soon as possible."

Many military analysts say any Israeli attack will concentrate on hitting four key Iranian nuclear facilities -- the uranium-enrichment plants at Natanz and Fordow, the heavy-water reactor outside Arak, and the uranium conversion facility near Isfahan.

The Israeli air force has three possible routes to those targets -- north over Turkey, south through Saudi Arabian airspace or the central path over Jordan and Iraq.

Turkey is out following Ankara's May 2010 rupture of its longstanding alliance with Israel.

Saudi Arabia, Iran's archrival in the region, would likely privately applaud any Israeli operation to set back Iran's supposed drive to acquire nuclear weapons but it would probably stop short of opening up its air space to Israel's strike jets. However, some Israelis suspect Riyadh would turn a blind eye and feign ignorance.

U.S. defense analysts say the Jordan-Iraq route would be preferable, since Iraq has no air defenses to speak of after U.S. forces completed their withdrawal in December.

This is where the Israeli air force's lack of refueling aircraft becomes a crucial factor. The distance to target and back via the Iraq route is roughly 2,450 miles.

To effectively clobber the Iranian targets the Israelis would need to employ at least 100 of their strategic strike aircraft. These currently comprise 101 U.S.-built F-16I Sufas and 25 F-15I Ra'ams customized for the Israelis.

The F-15I, for instance, has a combat radius of 2,780 miles but with a full load of bombs and missiles these jets would probably need two in-flight refuelings during the mission.

Israel's capability in this regard isn't enough to cope with 100-plus strike jets to and from targets in Iran.

In recent years the Israelis have quietly acquired seven Boeing KC-707 tanker aircraft from the United States, along with at least five Lockheed C-130 transport jets that have been converted to the tanker role.

"Theoretically," said U.S. military analyst David Isenberg of the Cato Institute, "the Israelis could do this -- but at great risk of failure.

"If they decided to attack Natanz, they would have to inflict sufficient damage the first time -- they probably would not be able to mount follow-on strikes at other facilities."

The Israelis, U.S. officials say, have accepted their limited options and that, unlike the United States, they don't have the firepower to deliver a knockout blow to Iran's nuclear project, only set it back by a year or two.

All key sites are protected by modern Russian air-defense systems, so the Israelis would also probably need electronic warfare aircraft to blind Iran's defenses, as they did in the September 2007 strike that destroyed a North Korean-built nuclear reactor in eastern Syria.

Besides, the Iranians have reportedly been dispersing their nuclear facilities and burying them deep underground to protect them from bomb and missile attacks.

So the Israeli air force will need a lot of GBU-28s to get the job done.

In recent days, an added wrinkle has reportedly emerged.

Israel's Debka Web site, believed to be closely associated with Israeli intelligence, claims Russia has upgraded an electronic surveillance station south of Damascus tailored to extend Tehran's early warning system of an Israeli or U.S. attack from the Mediterranean.

Netanyahu leaves US with assurances on Iran
Washington (AFP) March 6, 2012 - Israeli leader Benjamin Netanyahu left Washington Tuesday with assurances that the United States is prepared to use force to prevent Iran from getting a nuclear weapon, just not yet.

Netanyahu, who met with President Barack Obama on Monday and Secretary of State Hillary Clinton on Tuesday, put the world on notice that his patience was wearing thin and, if necessary, he would launch unilateral strikes.

"As prime minister of Israel, I will never let my people live in the shadow of annihilation," he told 13,000 delegates in a keynote speech on Monday night at the American Israel Public Affairs Committee (AIPAC) conference.

"Unfortunately, Iran's nuclear program has continued to march forward. Israel has waited... for diplomacy to work, we've waited for sanctions to work. None of us can afford to wait much longer."

Sitting alongside the president at the White House before going into talks on Monday, Netanyahu told Obama that Israel must remain the "master of its fate," in a firm defense of its right to mount a unilateral strike.

Obama, who assured Netanyahu that he has Israel's "back," stressed that he sees a "window" for diplomacy with Iran, despite rampant speculation that Israel could soon mount a risky go-it-alone military operation.

While no one knows exactly what was said behind closed doors in the Oval Office, Obama publicly kept to a far more dovish line and appeared notably at odds with Netanyahu over just how immediate the Iranian threat is.

"This notion that somehow we have a choice to make in the next week or two weeks or month or two months is not borne out by the facts," he told a press conference Tuesday.

But addressing AIPAC on Sunday, Obama recognized Israel's right to take action on its own and said he was prepared to use force if necessary to snuff out an Iranian nuclear threat.

Obama acknowledged "Israel's sovereign right to make its own decisions about what is required to meet its security needs."

"I have a policy to prevent Iran from obtaining a nuclear weapon," he said. "As I've made clear time and again during the course of my presidency, I will not hesitate to use force when it is necessary to defend the United States and its interests."

World powers on Tuesday responded to Iran's new willingness to discuss the nuclear issue with an offer of talks, which Obama said would "quickly" show whether the Islamic republic was serious about avoiding war.

Obama, seeking a second term in November, argued that Iran was now feeling the "bite" of tightening sanctions though cautioned he did not expect a breakthrough in a first set of negotiations.

He also slammed Republican candidates for their hawkish statements demanding military action on Iran, after leading candidate Mitt Romney earlier said "thugs and tyrants" only understood American readiness to use power.

"This is not a game, and there's nothing casual about it," Obama said.

After meeting Clinton, Netanyahu held talks Tuesday with congressional leaders before flying home.

"We've had a very good visit in Washington, first in our discussion with the president in the Oval Office... and now culminating in this remarkable display of solidarity here in the Congress of the United States," he said.

"I go back to Israel feeling that we have great friends in Washington."

House Speaker John Boehner, a Republican, said: "The looming threat of a nuclear Iran cannot be ignored. Now is the time to stand together and we are here today to tell the prime minister that Congress intends to do so."

In Brussels, EU foreign policy chief Catherine Ashton, speaking on behalf of Britain, China, France, Germany, Russia and the United States, reiterated an offer to resume talks with Tehran, which denies it is seeking the bomb.

The Obama administration says it does not believe Iran has taken a decision to develop a nuclear weapon, or that the time is right for military action, preferring to give biting new sanctions time to work.

But Israel, which sees a possible Iranian nuclear weapon as a threat to its very existence, claims Iran may be on the cusp of "breakout" capability -- when it could quickly build a nuclear weapon.

In his speech to AIPAC, Netanyahu sought to minimize the differences between himself and the US president.

Obama "stated clearly that all options are on the table and that American policy is not containment," Netanyahu said. "Israel has exactly the same policy."