Who told us that? It's not true, the US does not have such a system, the missiles in the silos are ballistic missiles, not ABMs; there is no missile defense system in place; The US has been negotiating with eastern european countries to put a radar station there that would be part of a future ABM system, but especially since the financial crisis work in this area is slowing if not stalled and the Russians are against it. the US is testing anti-ballistic missles but the success has been spotty, even when the ABM knows exactly where and when the missile is coming from and when the dummy missile is dropped from a cargo plane (an easier to hit target) and even if an ABM system is put in place there is not guaranteeing success, it wouldn't be 'guaranteed' to work but it would provide some level of protection at a very high cost. One other thing, this ABM system would not work against a cruise (or other type) of missile launched from a strategic submarine-this is the most difficult type of interception because you never know where one of these subs are going to pop-up. This would have to be done by navy ships searching for subs, again if you don't find it, a single sub can launch dozens of warheads. Other problems with it, the attacking country can design missiles that avoid the ABMs, they could use anti-satellite missiles to attack the satellites that guide and detect the incoming ICBMs. etc. IMO ABM systems should be abandoned because they encourage other countries to procure more missiles, at greater cost to their societies, and don't deliver reliable protection. BTW Obama has pretty much cancelled the entire maned space program, a few more shuttle flights and it's over..so serious are current budgetary constraints.