COULD ISRAEL LAUNCH A NUCLEAR STRIKE AGAINST IRAN?

It's a poker game with high stakes and a degree of bluff. Israeli leaders refuse to rule out any option. They do not believe Iran's assurances it wants only nuclear energy. Noting re-elected Iranian President Mahmoud Ahmadinejad has said Israel should be "wiped off the map", Israel says an Iranian bomb is a threat to its very existence that it will simply not tolerate.

Last year, however, it emerged officials were making plans for how Israel might live with a nuclear Iran in a state of mutual deterrence. And an opinion poll last month showed most Israelis would not expect a nuclear Iran to attack them.

Since becoming prime minister in March, Benjamin Netanyahu has, aides say, made ending threats from Iran a defining element of what he sees as his personal role in Jewish history. A 1981 Israeli air strike that destroyed Iraq's only nuclear reactor, as well as a strike in Syria in 2007 that remains cloaked in mystery, set historical precedents. Despite a policy of silence, few doubt Israel has nuclear weapons that could hit Iran.

WHAT MIGHT HOLD ISRAEL BACK?

It is not clear how Israel would define achieving its goal of preventing Iran acquiring nuclear weapons, but a pledge from Iran to forswear such arms, backed by some form of supervision and intelligence data, might be a minimum. Much, of course, will depend on Iran's actions and on U.S. President Barack Obama and others, who are pressing Iran through sanctions and diplomacy.

While many analysts doubt Iran's denials of military intent, some say Iran may be content with showing it has the potential to go nuclear quickly, without actually arming itself.

In the meantime, were Israel to consider a unilateral strike on it Iran it would have to weigh several major risks:

-- of retaliation, not just from Iran but its allied guerrilla groups, Lebanon's Hezbollah and the Palestinian Hamas

-- of economic and diplomatic backlash from U.S. and allies

-- of a failed attack still triggering the above reactions

WHAT ARE THE KEY ELEMENTS IN TIMETABLE?

First, Iran's technology: Israel's national security adviser said last week it had passed a "red line" in terms of being able to make its own nuclear explosive but could not make significant amounts nor yet put viable nuclear warheads on its missiles. Mossad chief Meir Dagan, seen as a key figure in Israel's Iran policy who has just had his mandate unusually extended to 2010, said last month Iran could have a viable warhead in 2014.

Second, the wider diplomacy: The G8 last week gave Iran until September to start talks or face new sanctions. In May, Obama told Netanyahu that "by the end of the year" he expected to have a sense of whether diplomacy was succeeding with Iran.

WOULD ISRAEL GO IT ALONE, WITHOUT U.S. BACKING?

Obama, at odds with Netanyahu over Jewish settlement in the West Bank and peace moves with the Palestinians, said last week he had "absolutely not" given Israel a green light to attack. He was responding to a remark by his vice-president that Israel had a sovereign right to act if it felt "existentially threatened".

Israel would be reluctant to anger its key ally. But as Netanyahu's security adviser Uzi Arad said last week, recalling the Holocaust: "We are always alone. Sometimes we have partners and lovers and donors of money, but no one is in our shoes."

Some question whether Israel's U.S.-armed military has the range and firepower to destroy Iran's nuclear facilities without U.S. help. Analysts say Israel might be content with slowing any nuclear arms programme, hoping for political change to end it.

Talk of an Israeli unilateral strike may also be part of a tactic of deterrence. Arad again: "The more credible and concrete the option, the less likely that it will be needed."

HOW MIGHT ISRAEL ATTACK IRAN?

Overt or covert? Israel has been developing "cyber-war" capabilities that could disrupt Iranian industrial and military control systems. Few doubt that covert action, by Mossad agents on the ground, also features in Israeli tactics against Iran. A key advantage of sabotage over an air strike may be deniability.

Militarily Israel can also deploy the following forces:

AIR -- 500 combat aircraft, including F-15s and F-16s able to bomb Iran's west, and further with aerial refuelling, a technique for which the air force has been training. Planes could overfly hostile Arab states using stealth technology. Armed with "bunker buster" bombs that could be released with accuracy outside Iran's airspace. Israel is also assumed to have dozens of Jericho missiles designed to carry nuclear warheads to the Gulf. It is unclear Israel would make a pre-emptive nuclear strike.

LAND -- Special forces could be deployed on the ground, to spot targets, and also possibly destroy them with sabotage.

SEA -- Israel sailed one of its three German-made Dolphin submarines into the Red Sea through Suez last month, opening a way to the Gulf. The submarines are believed to be capable of firing nuclear and conventional missiles. -Reuters