Two antitank missiles were destroyed in flight by laser beams in tests conducted earlier this year by the Navy, the first time lasers have been able to strike down fast-moving targets of any kind.

The lasers were high-energy devices that destroyed a pair of TOW antitank missiles flying at speeds of 250 miles an hour. The laser beams that struck the missiles were fired from a little more than a mile away at a test range run by TRW, Inc. at San Juan Capistrano, Calif.

These details were first published by Philip J. Klass in the magazine Aviation Week & Space Technology, which is running a three-part series on the use of lasers as weapons. Klass said the details of how the laser destroyed the missiles were secret.

"The laser either burned a hole in the missiles and blew them up," Klass said, "or so weakened their air frames that they became rubbery in flight and disintegrated."

Lasers as weapons have been under development for at least five years at Kirtland Air Force Base in New Mexico, where the Air Force flies a test laser in an airplane to track dummy warheads that act as simulated ballistic missiles speeding toward earth. So far as is known, the Air Force laser has never managed to burn enough holes in any of the warheads to destroy them.

Laser light is a beam so narrow and tightly bunched that it creates enormous heats on the surface of objects it strikes for any length of time. The lasers used in the Navy tests in California were continuous lasers, meaning their beams did not have to be pulsed on and off as do many lasers.

The significance of the California laser tests is that Navy experimenters were able to track high-speed missiles in flight and focus the laser light on the moving targets for as long as 10 seconds. The heat that built up on the missiles' air frames was enough to weaken them and either tear them apart or force them out of control.

Twice in the past, lasers were used by the Air Force and Army to destroy pilotless drones but each time the drones were slow-moving targets.

In 1973, the Air Force used lasers to knock down winged drones at Kirtland AFB, and in 1976 the Army used lasers to destroy helicopter drones at the Redstone Arseral in Alabama.

But even the missiles shot down by the Navy lasers do not fly at the supersonic speeds of today's aircraft and missiles. Antitank missiles are a far cry from ballistic missiles or air-to-air missiles.

Long popularized as a death ray, the laser has numerous shortcomings as a superweapon. Its beam cannot penetrate clouds, fog or rain. It is also difficult to aim, partly because targeters never know if they are high, low or wide if they miss the target.

The way laser weapons have been aimed in past tests is to bounce the beam off a swiveling mirror that tracks the target at the same time. One trouble with this is that the mirror distorts and bends the beam somewhat, causing some inaccuracy.

The California laser tests prove one thing: that lasers could be extremely effective weapons in space, where there are no clouds, fog or rain to block, bend or distort the beam.