The contrast could not have been clearer: First, television footage of Israelis in gas masks carefully sifting through rubble of Iraqi Scud attacks on Tel Aviv. Then, live pictures of a U.S. Patriot missile streaking skyward to score a direct hit on an Iraqi Scud.

With these TV images, Americans had vivid evidence of why ballistic missile defense is important as well as how effective it can be.While the images are still fresh in our minds we should focus on what these events teach us: Americans and our allies should never again be defenseless against ballistic missile attack; and we need not be.

The Patriot is effective against short-range, relatively slow-flying missiles like the 1970s vintage Iraqi Scuds.

But the world is already full of missiles far too sophisticated for the Patriot to intercept. In testimony to the House Armed Services Committee, CIA Director William Webster warned that between 15 and 20 developing nations will possess ballistic missile capabilities by the end of the century; six of them will have nuclear capabilities.

A new generation ballistic missile defense will be needed to protect against these advanced weapons.

To meet this threat, the United States has been engaged in the Strategic Defense Initiative, SDI, and the results are very promising.

SDI research is focusing on more advanced theater ballistic missile defense systems as part of Global Protection Against Limited Strikes, the refocused SDI program to provide a global protection system that would rely on both ground-based missiles and space-based satellites.

SDI theater defense programs will be able to counter the threat of tactical ballistic missiles within the next four to five years. One of them is being developed jointly by the United States and Israel to protect Israel from missile threats.

The ERINT (Extended Range Interceptor Technology) and THAAD (Tactical High Altitude Area Defense) could be deployed anywhere U.S. or allied citizens or forces need protection.

Some SDI opponents have argued that today's theater defenses like the Patriot are all we need. They are wrong for several reasons.

First, as noted, Patriot's capabilities are stressed with missiles much beyond the capabilities of Scuds. Second, Patriot protects only a relatively small area. ARROW and THAAD will protect an area more than 10 times greater. Third, theater defense missiles cannot be effective against intercontinental ballistic missiles, a threat that will increase as more nations acquire that capability.

As a practical matter, it would be impossible to protect all of the assets in the continental United States, all of our forces deployed abroad, ships at sea and our allies, by installing batteries of theater ballistic missiles around them.

Only a satellite system provide such global coverage.

"Brilliant Pebble" satellites orbiting above Earth could detect and, upon ground command, intercept from above, missiles literally fired from or to anywhere on Earth. Just as we developed "look down-shoot down" anti-aircraft capability when limitations on ground radar and anti-aircraft missiles became apparent, so too must we have "look down-shoot down" capability against ballistic missiles. SDI will provide that through a combination of ground and space-based components.

The debate about SDI funding levels will not be decided wholly by the events in the Persian Gulf, but the lessons learned there will help us structure an intelligent defense for the future.

For now, we can be very grateful that decisions were previously made that are now providing protection from missile attack to military personnel and civilians alike in the Middle East.