North Korea's July missile volley raised legitimate concern about American vulnerability to ballistic missile and cruise missile attack. Hezbollah's rocket barrage of Israel demonstrated that terrorist organizations (non-state actors) can acquire and use missile systems.

The next step, for both North Korea and Hezbollah, is adding a weapon of mass destruction (WMD) -- most likely a warhead carrying either nukes or nerve gas.

The longer-range rockets Hezbollah used (for example, Russian FROG-7 variants) can be classified as short-range or "battlefield" ballistic missiles. With range exceeding 100 hundred kilometers, these missiles can strike well beyond the frontline.

There is good news. The United States isn't completely vulnerable. It possesses a nascent, "thin shield" ballistic missile defense.

The defense consists of bits and pieces of tactical and theater-level anti-missile programs supported by a dozen or so long-range missiles positioned in Alaska and Hawaii.

This defense has layers. The Patriot PAC-3 is designed for short-range, "point-target defense. The Patriot PAC-3 is a completely different missile from the Gulf War's Patriot PAC-2. The PAC-2 was an "enhanced" and "upgraded" anti-aircraft missile. The PAC-3 is a genuine anti-ballistic missile (ABM).

The Army's THAAD (Terminal High Altitude Air Defense) missile and the Navy's Standard-2 and Standard-3 missiles extend the "anti-missile umbrella." The Navy systems are particularly useful. They can be deployed on Aegis cruisers and destroyers. The Navy systems can quickly place anti-missile firepower in the Persian Gulf (to thwart a shot from Iran) or the Sea of Japan (to intercept a North Korean launch).

The Standard-3 missile had a highly successful missile test in June. In a July test at the Army's White Sands range, a THAAD intercepted a SCUD-type ballistic missile.

The nascent defense, however, is an inadequate defense -- I don't think that's a debatable point.

Yet it is a defense in being and a defensive system in the process of expansion. Though limited and frail, it demonstrated political utility in July when North Korea launched its missile volley. What do I mean by that? Japan -- a threatened ally -- asked for Patriot PAC-3s to bolster its defense. The United States agreed to provide them.

We also have a new U.S.-Japanese missile monitoring station in Japan, activated earlier this year. Continued...