What is the point of the Nuclear Security Summit?

President Barack Obama is hosting a Nuclear Security Summit aimed at securing all weapons-grade material around the world within four years.

As the summit of world leaders opened, Obama said: "We know that organisations like al-Qaeda are in the process of trying to secure a nuclear weapon - a weapon of mass destruction that they have no compunction at using."

WHAT IS THE POINT OF THE NUCLEAR SECURITY SUMMIT?As the name of the summit suggests, the aim is to prevent theft and smuggling of nuclear material. The main focus is on securing stockpiles of weapons-grade plutonium and highly enriched uranium, rather than the kind of run-of-the-mill nuclear waste that could be used to make a 'dirty bomb' - the destructive effects of which have been wildly overstated by the media in recent years.

The US also hopes that richer countries will agree to put hard cash behind efforts to secure fissile material - which can be used to create nuclear fission, the basis of an atomic blast.

Is there a problem?President Obama said at the summit opening that the possibility of a terrorist group getting hold of a nuclear weapon is the "single biggest threat to US security". Then, perhaps realising this was a global summit, he added: "If there was ever a detonation in New York City, or London, or Johannesburg, the ramifications economically, politically and from a security perspective would be devastating."

Ikia Amano, the head of the International Atomic Energy Agency, told the BBC: "The problem is that nuclear material and radioactive material are not well protected and member states need to better protect these materials against theft or smuggling."

"On average every two days we receive one new [report] on an incident involving theft or smuggling of nuclear material."

WHO IS AT THE SUMMIT? Among the 47 nations in attendance are India and Pakistan. These nuclear-armed states have fought four wars since partition in 1947 - and they are considered by many as the most likely protagonists in any nuclear war.

China, which possesses the fourth largest nuclear weapons capability, is also there and that has raised hopes that it will work with the US towards imposing sanctions on Iran, which is believed to be developing a nuclear weapon.

Kazakhstan, one of the world's top exporters of uranium, will also be a key player. France, perhaps the 'most nuclear' state in the world since it derives 80 per cent of its energy needs from nuclear power and has the third-largest nuclear weapons stockpile, has already said it has no intention of giving up its deterrent. Britain is represented by foreign secretary David Miliband.

WHO ISN't there?Iran, North Korea, Syria - and Israel. The first three were not invited by Obama because of concerns that they have violated, or want to violate, the nuclear non-proliferation treaty - interestingly, Pakistan, a "source of proliferation" according to the US, is present.

In this context, it is hard not to see the summit - indeed all of Obama's recent efforts to set a good example over nuclear weapons - as an elaborate attempt to isolate Iran and ensure sanctions are approved by the United Nations.

Iranian President Mahmoud Ahmadinejad dismissed the summit, saying: "World summits being organised these days are intended to humiliate human beings."

As for Israel, it is in truth represented in Washington, but while all the other countries sent their leaders, Israel sent Intelligence and Atomic Energy Minister Dan Meridor.

Prime minister Binyamin Netanyahu decided not to come after he became concerned that Turkey and Egypt were planning to lead an attempt to force Israel - which has an undeclared nuclear weapons capability - to open its doors to international inspectors.

HAS THERE BEEN ANY PROGRESS?Russia holds most of the 1,600 tonnes of highly enriched Uranium in the world which could be used to build a nuclear weapon.

The US and Russia are trying to set a good example: they signed a new START (Strategic Arms Reduction Treaty) last week to reduce their deployed nuclear weapons by 30 per cent to 1,550 each. Obama also set out a new US nuclear policy, the Nuclear Posture Review, aimed at preventing nuclear proliferation and the possibility of terrorists obtaining fissile material.

The most controversial aspect of the new policy was Obama's promise not to launch a nuclear attack against any state which is in compliance with the Non-Proliferation Treaty even if that country uses chemical or biological weapons against the US. The policy is clearly aimed at North Korea and Iran, which the US considers in breach of the NPT.

Obama singled out South Africa for special praise as being the only country to have abandoned a nuclear weapons programme - and the Ukraine got the summit off to a flying start by announcing it will deliver all of its uranium to Russia or the US for disposal by 2012.

WHAT NEXT?The Nuclear Security Summit will be followed up by a UN Non-Proliferation Treaty review conference next month which aims to strengthen the agreement. ·