The year is 1964. A young girl picks petals from a daisy and counts, "One, two, three, four..." Suddenly, another countdown begins-this one by a technician. "Three, two, one, zero." A rocket launches. A camera zooms in on the girl's frozen face; her eye becomes a screen in which the viewer sees an atomic mushroom-cloud. "These are the stakes," Lyndon Johnson intones. "To make a world in which all God's children can live, or go into the dark…"

That famous political ad was used, ironically enough, against Sen. Barry Goldwater-the man who wanted to protect America against a nuclear attack. Today that ad could more appropriately be used against those who don't want to protect America from destruction. I'm referring to those who argue that America should not be permitted to blast an incoming missile out of the sky-indeed, that the 1972 ABM Treaty bars us from doing so.

During the 1960s Robert McNamara, the architect of America's Vietnam War policy, formulated a strategic nuclear plan that was aptly named "MAD," for "mutual assured destruction." Designed to keep both the United States and the Soviet Union vulnerable to a nuclear attack by preventing the deployment of missile defenses, the policy was codified with the ratification of the ABM Treaty. The thinking: What madman would dare push the button if he knew his own cities would perish in a retaliatory attack?

Fast forward to 1998. The Soviet Union is gone, but the threat of a missile attack on the United States may be more real than ever. Not only is China a bona fide nuclear power-with missiles already aimed at the United States-but India and Pakistan have detonated nuclear devices as well. North Korea and Iran have been developing missiles that soon may be able to reach the United States. And a number of countries already possess missiles capable of striking U.S. allies and troops stationed abroad.

Although the ABM Treaty was a mistake, it doesn't have to bind us any longer. Many legal scholars say that since our treaty partner, the Soviet Union, no longer exists, the agreement is null and void. Even former Secretary of State Henry Kissinger, one of the treaty's architects, agrees it has expired.

Now before you start conjuring images of Star Wars and expensive sci-fi lasers, remember that technology has improved greatly since President Reagan launched the Strategic Defense Initiative (SDI) in 1983. Four years ago, The Heritage Foundation convened "Team B," a group of defense experts led by former SDI director Henry Cooper. Team B found that an effective missile defense system could be built by upgrading the Navy's AEGIS guided-missile cruisers. The cost of giving 22 AEGIS cruisers the ability to counter ballistic missiles would be about $3 billion-a mere pittance given a $1.7 trillion federal budget. More advanced defenses could be built later.

Need more evidence that the missile threat is real? Just recently a bipartisan commission headed by former Defense Secretary Donald Rumsfeld concluded that missiles from rogue nations could strike American cities with "little or no warning" in just a matter of a few years. This despite the fact that U.S. intelligence agencies keep telling us we have nothing to worry about. Of course, these are the same intelligence experts who had no idea India and Pakistan were about to explode nuclear bombs.

If even one nuclear missile reached the United States, millions could die within minutes. The United States needs to build a missile defense system. It's not just a defense consideration, it's a moral imperative.

As LBJ said back in '64, "The stakes are too high…"

Edwin J. Feulner is president of The Heritage Foundation (www.heritage.org), a Washington-based public policy research institute.