The US needs a new start in air defense. Existing systems are not integrated, not layered and are mediocre to poor performers. Since the 1950s, the US has struggled for solutions to missile threats.
Because the army and the Pentagon keep trying to improve the one system they have instead of creating a real competitive environment, the future for US missile defense and US security seems bleak.
Today no US city and no US missile base in the US has protection against ICBMs or any other threat. In California at Vandenberg AF Base and Alaska at Ft Greely, the US deploys the Ground Based Midcourse Interceptor (a total of 44 interceptor missiles).
The missile has a spotty record of tests ( 11 of the 20 [55%] hit-to-kill intercept tests have succeeded) and the Air Force is looking for a replacement missile. GBI is exoatmospheric and uses "hit to kill" technology; it does not have an active warhead.
In the Air Force approach, GBI with a new interceptor missile will still be limited to rogue missiles from North Korea (GBI is not deployed to deal with Iran). Even though the ABM Treaty was canceled, there appears to be no interest at the Pentagon or Congress for a real ABM capability to protect US territory.