In early October, U.S. officials accused Iranian operatives of planning to assassinate Saudi Arabia s ambassador to the United States on American soil. Iran denied the charges, but the episode has already managed to increase tensions between Washington and Tehran. Although the Obama administration has not publicly threatened to retaliate with military force, the allegations have underscored the real and growing risk that the two sides could go to war sometime soon -- particularly over Iran s advancing nuclear program.

The brutal clerical regime is doubtless a threat to its own people, though it does not rank particularly high in that respect in comparison to US allies in the region. But that is not what concerns the military and intelligence assessments. Rather, they are concerned with the threat Iran poses to the region and the world. The reports make it clear that the Iranian threat is not military. Iran's military spending is "relatively low compared to the rest of the region", and of course minuscule as compared to the US. Iranian military doctrine is strictly "defensive, designed to slow an invasion and force a diplomatic solution to hostilities". Iran has only "a limited capability to project force beyond its borders". With regard to the nuclear option, "Iran's nuclear programme and its willingness to keep open the possibility of developing nuclear weapons is a central part of its deterrent strategy".

An imminent report by United Nations weapons inspectors includes the strongest evidence yet that Iran has worked in recent years on a kind of sophisticated explosives technology that is primarily used to trigger a nuclear weapon, according to Western officials who have been briefed on the intelligence. But the case is hardly conclusive.