It went underreported in the news, but two weeks ago U.S. intelligence sources confirmed that North Korea is preparing a late-summer launch of its Taepo Dong 2 missile, an ICBM capable of reaching Alaska or Hawaii. This will make North Korea, an unstable regime long hostile toward the United States, one of only a few countries able to strike U.S. soil with long-range missiles. The question is: What can the United States do about it?

A partial answer came on June 10 when, over the early morning skies of New Mexico, the Army's new anti-missile system successfully intercepted a target ballistic missile launched 120 miles away. Without using an explosive warhead, the interceptor destroyed the incoming missile by crashing into it-a very difficult feat-at an altitude of almost 60 miles.

The Theater High Altitude Area Defense (THAAD) is designed to defeat intermediate-range missiles and, as such, will not be able to stop North Korea's Taepo Dong 2. But it proves that "hit-to-kill" technology can work-something critics of missile defense have long denied. Indeed, as recently as three months ago, during congressional debate over a bill committing the United States to field a national missile defense, opponents refused to admit it could be done. "Hit-to-kill technology is nowhere near feasible," said Rep. Tammy Baldwin, D-Wisc., in a typical dismissal.

The challenge now is to build an effective defense against long-range missiles that builds on THAAD's success. This will require much more development and testing, and much more support from Congress and the administration. The fact that it took the Army seven tests to score the first THAAD "hit" is not an argument against missile defense but an argument for investing more in anti-missile technologies.

Unfortunately, the United States cannot make progress as long as the Clinton administration observes the restrictions of the 1972 Anti-Ballistic Missile (ABM) Treaty. The recent decision by President Clinton and Russian President Boris Yeltsin to revisit the ABM Treaty is meaningless. As a matter of international law the treaty is defunct since our signing partner, the Soviet Union, ceased to exist in 1991. Misplaced devotion to the ABM Treaty hampers the development, testing and deployment of certain kinds of missile defenses, ensuring that any system will be less capable than it otherwise could be.

Something must be done to free engineers and scientists from the constraints imposed on them by the Administration and allow them to create the most effective ballistic missile defense possible. As a first step, the administration should remove barriers erected during the president's first term that prevent the successful testing of missile defenses such as the sea-borne Navy Theater Wide (NTW) system.

The NTW system would use "hit-to-kill" technology similar to that demonstrated in the THAAD test. The Administration's policy, however, bars the testing of the NTW system against long-range ballistic missiles, including North Korea's Taepo Dong and a new class of missile China is now developing with stolen U.S. nuclear and missile technology.

Congress should require that the NTW system be tested against such longer-range missiles. To increase the likelihood of success, Congress also should insist that the speed of the NTW's interceptor not be slowed to meet the administration's restrictions and that the NTW be allowed to use external sensor data, including data provided by satellites.

Such a system, once fully tested, would deploy 650 interceptors on 22 of the Navy's Aegis ships to defend U.S. territory against a limited ballistic missile attack. Unlike the president's proposed missile defense, which would consist of one or two ground-based interceptor sites, a sea-based system would allows ships to patrol off the coast of North Korea, China or other nations and destroy missiles shortly after they leave the launch pad. This "ascent phase" intercept ability is necessary to destroy a target missile when it is easy to track and still traveling at a relatively slow speed. It would also destroy the missile before it releases decoys or "penetration aids."

No one denies that missile defense is difficult, but one of America's strengths is that it does not hesitate to take on technological challenges. Building a missile defense for America is no more difficult-and just as important-as that other great technological challenge of our age: putting a man on the moon.

Baker Spring is a senior defense policy analyst at The Heritage Foundation (http://www.heritage.org), a Washington-based public policy research institute.