Recent media reports suggested that Britain's military is preparing options for joining a strike against Iran. But this is mainly sabre-rattling. It is highly unlikely that the UK government will sanction such attacks at present.
Military strategists may well be conducting paper studies on theoretical options in response to a hypothetical request. One of the things they certainly should look at is what to do with UK military assets in the region should a regional war break out. Such scenario-building is routine for strategists. But this does not mean that an attack has become more likely.
Indeed, the scope for the government to slip past us fateful decisions about committing armed forces has narrowed, especially since the 2003 Iraq war.
Before the UK went to war with Iraq, military leaders asked the government for a statement that an attack would be legal. They were served up a strained interpretation of the Iraq ceasefire resolution.
Prior to any future UK participation in war, the military, parliament and the public will require an answer to the same question about legality. Before participating in the Libyan conflict, David Cameron delivered an answer clearly and explicitly - that intervention was legal.
The Libyan conflict also tested the concept and practice of the one-year-old UK National Security Council, tasked with overseeing national security and collective cabinet-level decision-making on key foreign policy issues. The NSC would have to consider the legality of war with Iran, including the legality of indirect participation. The negative effects of war on other UK interests would also need to be assessed against the alternatives, including deterrence and containment of Iran.
According to The Guardian, a campaign against Iran could involve surveillance, the use of Diego Garcia to launch attacks, and aerial refueling. The article quotes a UK official as suggesting that any UK involvement would be 'cosmetic': however, there is no such thing as 'cosmetic' involvement in a regional war.
It is highly unlikely that the Attorney-General would advise the NSC that a pre-emptive attack on Iran by any country - in current circumstances - would be legal. There is no real and imminent military threat from Iran sufficient to invoke the right of anticipatory self-defence. (For more on this see the Chatham House report Iran: Breaking the Nuclear Deadlock, which sets out argumentation on imminence, necessity and proportionality in responding to threats).
With the Libya conflict now drawing to a close, and a new IAEA report in the offing containing a restatement with new detail of concerns about possible military dimensions to Iran's nuclear programme, Iran has resumed its position as the main focus of diplomatic concern.
Iran has been conducting research and development into weapons-linked technology, accumulating low-enriched uranium, hardening its sensitive installations and moving equipment to underground sites. But this is not news. Nor is it enough to change the facts about the current military threat or the legal parameters for addressing Iran's behaviour. Over the past ten years, a mix of sanctions and aggressive sanctions has not managed to prevent Iran from moving closer towards nuclear weapons capability. Imaginative diplomacy is needed more than ever to strengthen the international non-proliferation regime and reduce the chances that Iran will ever deploy a nuclear weapon.