The U.S. Army, returning to an age-old strategy used extensively by the Soviet military, is increasing its use of decoys and fake targets in hopes of outsmarting an enemy's modern weapons.

Decoys such as canvas tanks and plastic soldiers could make the Army in battle seem twice as large as it really is. And if telling seems to give away the secret, the Army points out that the enemy still does not know which half is real.

"We will always be outnumbered conventionally. These {decoys} are a force multiplier," said Stephen P. Rosa, vice president of TVI Corp., which developed fakes such as an M1 tank and trucks.

The canvas, two- and three-dimensional tanks made at TVI's 50-worker plant in suburban Beltsville look real both to the naked eye and to heat-seeking thermal targeting systems used at night.

An unassembled front-view M1 weighs about 25 pounds and collapses into a 4-foot-by-2-foot duffel bag. In less than three minutes, one soldier can assemble it and plug in a generator to warm up its thermal "signature." With a tape recorder and speakers, a couple of soldiers can sound like an entire tank battalion.

A fake M1 costs about $3,500, compared with about $3 million for a new M1.

"Deception really is the second goal. Survivability is the first," said Rosa. "Decoys are credible targets . . . . They allow the real vehicles to move around" and increase the survival rate in battle.

The Army has about 4,000 real M1 tanks and plans to outfit each with at least one fake M1, at a cost of about $7.5 million, said Maj. Andrew Fallon of the Army's budget office.

Deception has been a key element in military strategy since the Trojan Horse. German Gen. Erwin Rommel fooled Allied forces in North Africa during World War II; the British fooled the Germans, and the Israeli army today regularly uses deceptive radio chatter.

But the Soviets are thought to be the most adept, with an arsenal including pseudo ballistic missiles and entire fake armies under a branch of the military called the Principal Directorate of Strategic Deception.

"We know they make decoys of the highest order of equipment, even as much as making fake missile silos," Rosa said.

Fallon said the Navy is developing decoy ships, and the Air Force has ground decoys of F16 fighter jets that can turn a bare airstrip into a fake air base.

The decoys are made from blown-up photographs of the real things. They look remarkably real at a glance, which in battle is all an enemy would get before deciding whether to fire, Rosa said.

The canvas used for the tanks, jets and trucks is lined with a thin plastic film first developed at TVI as a heating element for ceiling panels, said Alex DeFonso, a founder and vice president of TVI.

By mixing the concentration of the plastic sheets, designers can create thermal images of a vehicle's wheels, engines and armor. The thermal and visual images are so realistic that even soldiers in exercises were fooled. "You may have the knowledge they are there, but it becomes impossible to discern if {the tanks} are real or fake," Fallon said.

The tanks can even survive one or two hits, which go right through without knocking the decoys down. "The enemy doesn't see a flash, and he thinks he missed," DeFonso said.

The Army is developing more elaborate decoys, including electronically generated fake targets, Rosa said.