If Israel hit Iran's nuclear facilities, would Hezbollah, Iran's allies in Lebanon, join in to retaliate? Would America step in to help its best friend in the Middle East? This filmed simulation shows a group of Israeli ex-spooks, former politicians and military officials split into teams to role-play the consequences. I have not seen the full film, but was in the cutting room for a couple of days helping with translation and the scenes I saw were compelling. Team Israel, taking stock of Iranian missile attacks on civilian targets, makes the operational assumption that the situation won't spiral totally out of control.

The documentary has an interview with an Iranian former nuclear negotiator and foreign policy adviser, who returns the simulated salvo by saying that Israel has grossly underestimated Iran's capacity for retaliation. Iran, he says, would assume American complicity in any Israeli attack and take aim at US targets in the Middle East. When the US staged their own simulation of this same situation, in March, it predicted that an Israeli strike would lead to a wider regional war.

the UK is thinking about putting warplanes in the Persian Gulf as tensions rise. And American military commanders have warned Israel that an attack on Iran could stunt US action, by cutting off key logistics support from Gulf countries that host US bases.

Foreign politicians and officials who took part in two G20 summit meetings in London in 2009 had their computers monitored and their phone calls intercepted on the instructions of their British government hosts, according to documents seen by the Guardian. Some delegates were tricked into using internet cafes which had been set up by British intelligence agencies to read their email traffic.

The G20 spying appears to have been organised for the more mundane purpose of securing an advantage in meetings. Named targets include long-standing allies such as South Africa and Turkey.

According to the material seen by the Guardian, GCHQ generated this product by attacking both the computers and the telephones of delegates.

The order, announced by the interior ministry in Manama on Tuesday, is the most-far reaching attempt to quell unrest in the Gulf kingdom since martial law was imposed last year.

Bahrain, where a Sunni minority rules over a Shia majority, is often described as lying on a sectarian fault line of the Arab world and on the frontline of a tense confrontation between Iran and its Gulf Arab neighbours.

Bahraini observers said the move appeared to reflect divisions and hesitation within the government and the lack of dialogue between it and the opposition. "The situation is stagnant and there is no horizon for a political solution," said Mansoor al-Jamri, editor of al-Wasat newspaper. "They are tightening their grip, but this is not a crackdown. That will mean mass arrests and opening the jails and taking senior people into custody."

Russian President Dmitry Medvedev, whose country shares U.S. fears about Islamist militancy in Central Asia, said the political system set up by Sunday's referendum could bring extremists to power or cause the collapse of the state.

Interim leader Roza Otunbayeva, speaking before the first results were known on Sunday, said Kyrgyzstan -- which lies on a major drug trafficking route from Afghanistan -- had embarked on a path to establishing a "true people's democracy."

Official results showed that with almost all votes counted, 90.6 percent of voters backed a new constitution paving the way for a parliamentary election in October.

President Barack Obama won rare praise from Moscow for scrapping that plan, which the Russians suspected was aimed against them. But the thaw did not last long. Last September, Washington announced what it called the Phased Adaptive Approach (PAA) to missile defence. This new system would start by stationing missile defence assets in south-east Europe, and slowly spread its web to the centre and finally the north.

As part of the PAA, Romania has announced that it will accept up to 24 land-based interceptor missiles. Talks with the US on the details will begin soon. And the Bulgarian government has offered to play host to the radar component which complements the missiles.

Romania says there are several differences between the new US plan and the earlier, Czech-Polish version.

Fresh from his success in signing a new strategic arms reduction treaty with the Russians in Prague, US President Barack Obama is hosting a nuclear security summit in Washington DC.With some 47 countries in attendance it will be one of the largest gatherings of its kind in the US capital since the late 1940s. This will be the third element in a nuclear season that began with this month's unveiling of the Obama administration's nuclear strategy, the Nuclear Posture Review. This identified nuclear proliferation - the spread of nuclear weapons and the danger that they might fall into the hands of terrorist groups - as now the key nuclear threat to America's security. That was step one. Step two was the meeting between Mr Obama and his Russian counterpart, Dmitry Medvedev, in Prague that got the strategic arms reduction process back on track. Step three will be this week's Nuclear Security Summit in Washington. All three events are aimed at strengthening Mr Obama's hand as he heads into step four: the review of the Nuclear Non-Proliferation Treaty (NPT) scheduled for next month in New York.

The threat here is not only from governments with a desire to own nuclear bombs or nuclear-tipped missiles. A far more pressing concern comes from the potential nuclear ambitions of non-state actors or terrorist groups. Their goal may be to obtain a small nuclear device but equally they may just want to get hold of radioactive material to build a so-called "dirty bomb". This uses conventional explosives to spread radioactive material over a wide-area.

So the goal of this summit is to batten down the hatches on nuclear materials - especially the fissile materials that might be used in bomb-making, plutonium and highly-enriched uranium - but also the more widespread sources of radioactive substances that could be used for a "dirty bomb". President Obama's goal is to obtain agreement upon a plan to secure all such vulnerable nuclear material within four years. Much will depend upon the detail.