The high tech missile shield protecting Guam and US mainland

Bill Gertz:

Amid growing missile threats from North Korea, American missile defenses based in Alaska, California, and Guam, as well as on Navy ships, are capable of knocking out North Korean nuclear missiles, according to military leaders and experts.

Missile Defense Agency Director Air Force Lt. General Samuel Greaves said Wednesday he is confident current defenses would be effective against Pyongyang's missiles.

"Yes, we believe that the currently deployed ballistic missile defense system can meet today's threat, and we've demonstrated that capability through testing," Greaves told a conference in Alabama.

Contrary to critics who say ground-based interceptors and naval anti-missile systems are unreliable, retired Air Force Lt. Gen. Trey Obering, a former MDA director, says the Ground-based Midcourse Defense (GMD) provides the best protection from a long-range North Korean strike.

Yet other shorter-range defenses such as the land-based Terminal High Altitude Area Defense, or THAAD, and the Navy's ship-based Aegis SM-3 missiles can knock out medium and intermediate-range North Korean missiles, and if given enough satellite warning could attack North Korea's ICBM warheads, he said.

"Any interceptor can intercept any missile, given the right parameters," Obering said in an interview.

"I have high confidence that if we were attacked by North Korea we would be able to defend ourselves."
...
The Pentagon is developing an advanced kill vehicle that will be added current interceptors in Alaska and California. New technology is also available to deal with maneuvering warheads.

Hyten said he would favor building space sensors and better interceptors before setting up a third based on the East Coast for the Ground-based Midcourse Defense.
...

I think the best missile defense is a pre-emptive attack against the North Korean program.  But it is good to have these backup systems in place in case they are able to launch one of theirs.  It is likely that the US will need to use the shield since it is unlikely that North Korea will back away from its ambitions of nuclear extortion.