Others say keeping Gates could delay the change that Obama promised during his campaign, because it could lead to potential policy conflicts over missile defense funding and a speedy Iraq pullout.
In his reply President Bush invites the UK to "participate at an early stage in any program to replace the D5 missiles or to discuss a further life extension - for your purposes - of the D5 missile to match the potential out-of-service date of your new submarines".
The advent of new technologies like hit-to-kill missile seekers and advanced signal processors greatly increased the defensive potential of the system while reducing the danger of collateral damage.
If the critics are right -- a significant "if" -- about the imminence of effective countermeasures falling into the hands of potential adversaries, the argument is only reinforced for pursuing multiple means of acquiring layered missile defenses at the earliest possible time .
They've said all along the threat is really Iran and Iranian potential long-range missiles, and that's why they wanted to expand the American missile defense system to Europe.
All the legal constraints that had prevented use of sea-based systems in missile defense schemes disappeared, and engineers could begin thinking about exploiting the full operational potential of the Aegis combat system.