An enemy tests a weapon that could kill millions of your countrymen in the near future. Having worked diligently on a defense against such attacks, your government has one within reach. Then, suddenly, it pulls back on this effort.

You are puzzled. You see a defense budget that preserves funding for weapons programs to defend other nations, but cuts back on the very weapons that could defend you.

This is what the Obama administration is doing with the nation's missile-defense budget. In the same week the North Koreans tested a long-range missile, the Pentagon announced a $1.4 billion cut in our missile-defense budget. Under the knife are the programs that could defend us against missile attacks from North Korea and Iran - the most hostile regimes America faces today.

It's being done in the name of "restructuring" the missile-defense program. The administration is holding on to defenses against short-range missiles, while scaling back programs against long-range missiles - the kind North Korea and Iran recently tested.

This makes no sense. Defenses against short-range missiles are all very fine, but they are not the missiles that most threaten the United States. That would be North Korea's Taepodong-2 missiles tested April 5, which when fully deployed, could reach Alaska and California.

One target of the cuts is the Airborne Laser (ABL), an energy-directed weapon placed on a modified Boeing 747-400. The ABL is intended to knock down a long-range missile shortly after it leaves the launchpad - the best time for an intercept because its warheads have not yet been deployed in space.

Preliminary tests have been quite promising. An actual ABL intercept test could take place later this year. This "boost-phase defense" is precisely the kind of system needed to counter long-range nuclear missiles launched from North Korea or elsewhere.

Another budget casualty appears to be the Ground-Based Interceptor (GBI) program. Thirty-three GBIs are already - or will soon be - deployed in Alaska and California. But the budget eliminates the plan to ramp up to 44 by 2011.

That makes no sense. GBIs are the only operational systems capable of destroying a Taepodong-2 missile approaching the U.S. mainland. Shorter-range missiles fired from Aegis ships could defend Japan, Guam and perhaps Hawaii, but currently could do nothing to stop a missile heading for Alaska or California.

Most puzzling of all is the Pentagon's decision to kill the Multiple Kill Vehicle, which is designed to destroy missile stages and warheads in space. Its value is that it could potentially destroy multiple incoming warheads. It is not yet fully developed, but there are no showstoppers in its research, testing and development.

The same is true for the Space Tracking and Surveillance System (SSTS) sensor program, which could discriminate between real warheads and decoys in space. Both programs could prove vital in defeating an enemy's attempt to overwhelm our missile-defense system with countermeasures.

It would be understandable if we couldn't afford missile defenses. But that is clearly not the case. The $1.4 billion cut from the missile defense budget is 0.04 percent of the overall proposed federal budget. It's like a rounding error in an Obama bailout.

The roughly $10 billion we spend annually on all of missile defense amounts to only 13 percent of what local, state and federal government agencies pay for "first responders." I'm all for responding effectively to catastrophes, but surely we can afford a fraction of the "response" budget to stop a disaster before it happens. Besides, why is defending Americans from nuclear attack one of the few areas where the administration is showing any budget restraint?

"Missile defense doesn't work" is an old excuse. And false.

As Gen. Trey Obering, former director of the Missile Defense Agency, points out in a new documentary, "33 Minutes," the U.S. missile-defense program has long since proved that it can, in fact, "hit a bullet with a bullet." As he puts it, recent tests show "we are now able to hit a spot on a bullet with a bullet."

Missile defense is not just the last line of defense against a future North Korean or Iranian missile attack. It is the best line of defense. Diplomacy did nothing to stop the North Koreans from their latest test.

Despite U.N. Security Council resolutions, they tested anyway. You can be sure that if they ever decide to launch a missile against us or our allies, they will not be deterred by diplomacy, either.

Kim Holmes, a former assistant secretary of state, is a vice president at the Heritage Foundation and author of "Liberty's Best Hope: American Leadership for the 21st Century" (