The potential for conflict in the middle east to spread is illustrated by the way that the war in Syria continues to pose serious problems for neighbouring states in the region. The same principle may be at work with regard to what may be called the Israel-Iran crisis, where current developments over Tehran's claimed nuclear ambitions bring the possibility of military confrontation into sharper focus.
The most immediate question concerns whether Iran's new and deeply buried nuclear facilities are about to become invulnerable to Israeli military action. If that happens, Israel or the United States will - as and when either reaches the point of utter determination to curb Iran's nuclear programme - will have fewer military options available (see "America, Israel, Iran: the weapons trail", 30 August 2012).
The United States's current approach is a combination of economic and military actions - making further attempts to cut Iranian oil revenues, a major show of naval force in the Persian Gulf, missile-defence tests - backed by statements on what would be sufficient cause for US military action (see David E Sanger & Eric Schmitt, "To Calm Israel, U.S. Offers Ways To Restrain Iran", New York Times, 2 September 2012).
These, however, will have little if any effect. India and China remain committed to buying Iranian oil, and the Chinese in particular have invested very heavily in Tehran's oil-and-gas developments. The naval exercises and anti-missile tests will in fact be useful to Iran and China to help them gauge American capabilities, and further declarations of intent from Washington will help to guide their response to potential action.
At the same time, there is no doubt that sanctions are having a serious effect within Iran, especially in the medical field with shortages of pharmaceuticals and equipment (see Najmeh Bozorgmehr, "In Iran, sanctions take toll on sick", Washington Post, 4 September 2012). The government seems resolute in face of this. Tehran is also buoyed, the statement of Egypt notwithstanding, by the attention given across the global south to its hosting of the summit of the non-aligned movement.
Iran is also reported to have accelerated its nuclear programme, especially at the key underground enrichment facility at Fordow. This development is taken by many Israeli supporters of action against Iran as evidence of the need to strike, though the chair of the US joint chiefs-of-staff General Martin Dempsey has intervened to say that that such a military assault would be ineffective (see Jim Lobe & Gareth Porter, "Dempsey Muscle Forces Israeli Rethink", Asia Times, 5 September 2012).
There are two pieces of evidence, direct and indirect respectively, suggesting that Dempsey's message is significant. The first is that Washington's military connections with Israel are so close that the White House would know what was happening there almost minute-by-minute. Moreover, Israel would need direct assistance from the US X-band Radar - based in the Negev - in order to boost its anti-missile defences.
The second is that Republican presidential candidate Mitt Romney's team does not appear to want to make Iran an election issue, at least for now. The risk of war before the election is still present, and in any case crises can escalate very suddenly (see "America-Israel, Syria-Iran: war by accident", 19 July 2012). But these indicators suggest that Iran has probably calculated it has some months to play with, and can use that time well: partly to complete and fully protect the Fordow plant, partly to move ahead with medium-level enrichment to 20% Uranium 235. The latter is still allowed under International Atomic Energy Authority (IAEA) rules since it has medical and other use, though it is also much closer to the 85%-plus required for weapons.
All this most definitely does not mean Iran is, as of now, rushing for a bomb - merely that it is closer to providing at least a "ghost" deterrent. This would provide a double benefit: give Tehran a powerful negotiating card, and increase the capacity for it, in extremis, to go the whole way.
The Fordo dimension adds an extra layer of complication to this scenario. If Israel did decide at some stage to go to war, then making Fordow invulnerable would have the effect of making the conflict a much broader affair - for Israel would then be far more likely to try to damage and destroy a wider range of Iran's nuclear, defence, research and industrial facilities, using everything from cruise and ballistic missiles, numerous aircraft types and armed-drones, to cyberwar tactics and special forces.
This would be almost certain to prompt a major Iranian reaction, not least in the Gulf as well as from Hizbollah in Lebanon. Such an uncontrolled and unpredictable escalation would be deeply unpopular among many seasoned US military leaders.
Amid these considerations, it is routinely forgotten that Israel probably does have the capacity to destroy Fordow - but only with a nuclear weapon in the form of an earth-penetrating bomb. The US has such a system (the B-61 bomb in its recent mod-11 variant), and Israel possesses nuclear bombs close to the B-61 (such as the B61-11, which has the same basic physics package - a nuclear "core" - as other versions, though with different casing, fusing and guidance); thus, it would be very surprising if Israel hadn't developed a similar weapon.
But if Israel ever deployed that capability, the repercussions across the middle east and far beyond would be immense. An earth-penetrating warhead is especially dirty, releasing huge quantities of lethal radioactive fallout. Israel's decision to go that far would provoke worldwide opprobrium, and worse - the knowledge that at some point in the years that followed, a group would acquire the means to retaliate in kind within Israel (see "Israel and Iran:after the bombs fall", 5 April 2012).
The United States holds around sixty B61-11s, but their use against Iran is even less likely, not least because it is the only country with a conventional alternative - a bomb that could seriously damage the Fordow plant.
This is the 13.6-tonne "massive ordnance penetrator" (MOP), derived to some extent from the "massive ordnance air-burst" (MOAB) - known around the time of the Iraq invasion of 2003 as the "mother of all bombs"; the latter in turn derived from the BLU-82/B (so-called "big blue") 6.8-tonne slurry bomb of the Vietnam war era (see "America and Iran: big bombs, base politics", 22 October 2009).
The MOP was reported in 2009 to be nearing deployment, and is now ready (see Spencer Ackerman, "Air Force's Bunker-Buster Bomb Is Finally Ready", Wired, 26 July 2012). The Pentagon is acquiring an initial cache of thirty MOPs at a cost of over $200 million; each is reputedly capable of penetrating nearly twenty metres of reinforced concrete. Even this might not be enough for Fordow, where it is possible that multiple attacks and the development of more advanced variants would be required; but at present the bomb, at ten times the power of the current BLU-109 bomb, is the most effective candidate.
The initial stock of MOPs is at Whiteman air-force base in Missouri, the host site of its intended delivery-vehicle, the B-2 stealth-bomber. The 13.6-tonne weight of each bomb includes 2.4 tonnes of high explosive, the great majority of which is formed by hardened ferro-cobalt alloy casing.
Iran is well aware of all these details, and seems to have calculated that it can develop a facility sufficiently hardened that almost nothing can touch it - except a nuclear bomb or the MOP. Thus, any effective non-nuclear attack against it from early 2013 can only be carried out by the United States (see "America's war on Iran: the plan revealed", 30 June 2012).
This is particularly significant if Mitt Romney wins the election on 6 November 2012. A second term for Barack Obama means that diplomacy will have another chance - although an attempt by Israel to involve the US in a war with Iran can never be ruled out. A Mitt Romney victory, though, could create a very different situation; Israel could then seek some way of mounting a joint operation, rather than acting on its own with the very uncertain consequences that would entail.
This mix of elements includes, therefore, space for political choices and decisions. It is worth mentioining a particular salience for the United Kingdom, since the B-2's two key bases outside the United States are located at Fairford in Gloucestershire, western England and on the British territory of Diego Garcia in the Indian Ocean. Both will almost certainly be needed to stage any B-2 attacks against Iran. Any such request would face prime minister David Cameron with the consequence of embroiling his country in another destructive middle-east war. The stakes for all concerned are very high.