18 September 2009: BBC News
The Obama administration's decision to postpone deployment of a missile shield in Eastern Europe in favour of proven regional missile defence systems will provide better protection against Iran's current and near-future capabilities.
Obama's new strategy also contains the flexibility needed to respond to future Iranian missile developments should they emerge.
The missile defence system proposed by the Bush administration, which relies on a farm of interceptor missiles stationed in Poland and an advanced radar in the Czech Republic, is designed primarily to protect the continental United States and Western Europe from intercontinental and intermediate range ballistic missiles that Iran may one day develop.
The Eastern Europe-based system, however, could not defend south-eastern Europe, Turkey and Israel from the threats posed by Iran's current ballistic missile arsenal.
Moreover, the technologies behind the longer-range missile defence complex are not yet mature, and may not have worked as promised without upgrades to the X-band radar and additional development and testing.
These two shortfalls - unproven intercept capacity and the inability of the Bush-era architecture to defend against Iran's currently deployed medium-range Shahab-3 missile - apparently drove the Obama administration to shift strategy.
Changing threat
The newly proposed architecture relies on regional missile defence systems, such as the Aegis-based SM-3 interceptor, which are more mature, and designed specifically to engage and destroy short- and medium-range missiles.
That the regional missile defence assets are mobile, and do not require stationing in Eastern Europe - a politically sensitive issue in US-Russian relations - is a useful by-product of the new strategy, but not a determining factor.
The Iranian ballistic missile threat, however, is not fixed and will most likely change in the future.
Indeed, Iran is presently developing enhanced capabilities. Tehran began flight testing a new solid-propellant missile, the Sajjil, last year, and successfully injected a small satellite into low-earth orbit earlier this year using the Safir space launcher.
The Safir has limited military utility and could not be converted into a viable military, ballistic missile. The Sajjil modestly increases Iran's strategic reach, from about 1,500km for the Shahab-3 to about 2,000km for a one-ton payload.
But the Sajjil is several years from reaching operational status. Additional flight testing will be needed to validate the missile's performance parameters and reliability.
There are no indications to date that Tehran intends to develop intermediate-range missiles, those capable of hitting targets in Western Europe.
Iran has not attempted to cluster the Shahab-3 engines to build a more powerful first stage booster, as has been done by North Korea.
Nor is there any evidence that Iranian missile engineers are developing a larger diameter solid propellant motor capable of lifting larger payloads to distances beyond 3,000km.
The absence of such activities does not mean that Iran will not pursue longer range missiles in the future, but it indicates that Iran is many years away from establishing an ability to threaten Germany, France or the United Kingdom.
Advance warning
A recent study conducted by missile experts from the United States, Europe and Russia for the International Institute for Strategic Studies concluded that Iran does have the technical and industrial capacity to develop a new missile capable of reaching Western Europe.
Efforts to develop such a missile, however, generate unique signatures, such as ground and flight testing.
A review of ballistic missile programmes in the United States, Russia, France, China, Israel, India and Pakistan shows that flight test programmes typically require more than four years, and they are preceded by other observable activities.
These necessary developmental steps provide five to 10 years' advanced warning of new capabilities, enough time for the United States and Europe to deploy more advanced missile defences if necessary.
Should Iran undertake activities to develop a longer-range missile, the new Obama strategy would have ample time to respond.
An upgraded version of the Aegis-based interceptors, the SM-3 IIA, for example, which is at a late stage of development, could be deployed quickly to ships or land to counter improved Iranian missiles.
Moreover, the Obama administration has made clear that if Iranian missile development activities so dictate, the longer-range, Bush-era missile defence system could be resurrected and deployed to Eastern Europe.
But these are hypothetical developments that are many years away.
