And Europe cannot defend itself from a potential Iranian nuclear missile threat beacause....?
Good question. I like our European allies, certainly don't want to see them nuked by Iran. However, as I understood it, the big radar and GBIs former President Bush was planning on putting in Europe would have also defended us (the US), against the developing Iranian ICBM threat.
For my own reasons I'm admittedly a big fan of the AEGIS weapons system and the SM-3. Maybe it's just the idea of going literally from sea level to space that tickles my fancy. Heck, I may even buy a little Raytheon stock (maker of the SM-3) if obama continues to pursue this strategy. Anyway, great missile, big plans for it. Fine. But it is not as big nor as capable as the GBIs - that would've defended us too. When it comes to missiles, size matters. Bigger means more fuel, more total impulse, and better speed, altitude and range. That translates into a bigger engagement envelop, and a higher probability of kill against any given threat. ICBMs by definition fly faster and higher than regional theater threats. That makes them a tougher intercept.
Ok, I admit I do like the idea of more shots - more SM-3s as compared to the number of GBIs they were looking at. Hmm, maybe I will buy that Raytheon stock... ;-)