Dawn lifts the mist off the jungle canopy, and somewhere near this Amazon River outpost a small plane roars just above the treetops carrying a load of semi-processed cocaine into Colombia.

It happens more or less daily, sometimes two to three times a day, in this region of impenetrable forests and vast rivers where Colombia, Brazil and Peru intersect - a new frontier in the drug war.A potent mix of U.S. electronic surveillance and Peruvian air force shootdowns have disrupted the traffickers' old air routes since mid-1995.

Now drug pilots are increasingly making short, low-altitude flights using a network of jungle airstrips.

They spend just minutes on the ground in Peru, refueling and loading up with as much as a half ton of raw cocaine, which arrives by land and river on the backs and in the boats of locals.

The next hop is north to drug labs in Colombia's interior. Pilots skim the treetops to avoid the sweep of U.S. radar based in Leticia and upriver in the larger Amazon port of Iquitos, Peru.

The shift in smuggling patterns has overwhelmed law officers in the region, known as Three Corners. Struggling against the upsurge in traffic, they complain of being outgunned, outmanned and outsmarted.

"We routinely intercept radio transmissions so we know what time they fly. But there isn't much more we can do," said Capt. Gabriel Galvis, deputy police commander for Amazon state, Co-lom-bia's largest.

Galvis does not have a single plane or helicopter and the nearest Colombian government aircraft are at least two hours away, giving a drug-laden Cessna 206 or Piper Seneca ample time to slip away.

Peruvian and Brazilian air force planes are closer, but none of the three nations allow the others' military aircraft to enter their airspace. So the drug-runners use runways that hug the borders.

Natives fiercely loyal to their cocaine-rich paymasters guard and maintain the strips.

"The native people are on their side," said Galvis. He said they supply the pilots with food and gasoline and an early-warning network as impenetrable as the jungle itself.

At least 15 airstrips straddle the Peru-Colombia frontier, delineated by the Amazon and one of its tributaries, the Putumayo.

Sitting just inside Peru along the green oblivion that divides it from Brazil are 18 more runways - a third of them built in the past year, said Mauro Spositio, federal police chief in Brazil's Amazonas state.

Spositio estimates 100 tons of raw Peruvian cocaine went north through the highway-less region in the past year. "The small-plane traffic is intense," he said.

Until mid-1995, larger planes based in Colombia flew with near impunity directly to the alpine Peruvian valleys where 70 percent of the world's cocaine originates on coca bushes.

The pilots dropped off bundles of cash and picked up a few tons of semi-processed cocaine. Local Peruvian officials and military chiefs took bribes and looked the other way.

That all changed when a combination of ground-based and airborne American radar, U.S. Cus-toms Service executive jets and Peruvian fighter planes began a tightly coordinated interdiction campaign.

With orders to machine-gun suspected drug planes that refused to identify themselves and land, Peruvian A-37 fighters shot down at least seven planes as U.S. Customs agents looked on from their jets.

Gen. Jose Luis Rodriguez, the Peruvian air force's chief of operations, said narco-aviators are now charging the drug cartels three times what they did in 1994 to work his country's airspace.

But the drugs keep getting through. U.S. officials say there is no indication any less cocaine is entering the United States, while even more of the drug is reaching expanding markets from Brazil to eastern Europe.

"It's very complicated, a chess game. They do something and we have to react. And normally, they're a step ahead," Rodriguez said.

New smuggling routes have flowered: down the Peruvian rivers that feed the muddy Amazon from cocaine-growing valleys on the Andes' eastern slope and along jungle paths where peasants earn $100 for a three-day trek with 30 to 40 kilograms on their backs.

"There are a thousand ways to move the raw cocaine," said a Peruvian anti-drug commander in Iquitos who uses the nom-de-guerre "Maj. Maranon." "They do it in speedboats, or under floorboards in larger, rustic boats. They hide it under fruits and vegetables, or float it down river tied to logs with a buoy attached."

By the time it reaches the border airstrips, each kilo (2.2 pounds) is worth between $800 and $900.

Peruvian police have seized 2.8 tons of raw cocaine on the region's rivers over the past six months. But much is slipping through, Maranon said.

Iquitos state has 6,000 miles of navigable waterways, and traffickers have equipped river dwellers with radios and cellular phones to warn them of police patrols.

Trying to disable airstrips has also proven hard.

On Oct. 24, Peruvian anti-drug commandos dynamited huge holes in four clandestine airstrips. Less than a week later, the holes were filled or covered with concrete slabs.

"Destruction of clandestine airstrips has a very temporary effect," said Rodriguez. "And there are actually benefits for the community. The drug traffickers pay for the repairs, so it's giving the locals more income."

On Nov. 17, six Peruvian policemen escorting three drug-trafficking suspects through Bellavista, 20 miles west of Leticia, were attacked by hundreds of villagers who beat them with clubs and the flat sides of machetes.

The officers fired in the air but did not dare shoot at their attackers for fear of being killed - and villagers seized their weapons, said Gen. Jose Maman, the state police chief in Iquitos.

The three suspects - all village leaders - were freed and the police lieutenant in charge was so badly beaten he had to be flown out by helicopter for treatment.

At least two airstrips just across the border in Peru - Remanso and Estrecho - are actually guarded by Peruvian police in the pay of traffickers, Colombian police say.

Peruvian police did not dispute the charge, saying it was understandable considering that they are outnumbered and earn the equivalent of just $150-$200 a month.

In the riverside fishing hamlet of Santa Rosa across the Amazon from Leticia, the local Peruvian police commander, Capt. Gilberto Torres, and his five men explain their predicament.

"With six officers you're simply not going to take an airstrip when there are 40 armed men guarding it," officer Darwin Perez said of the odds against attempting to surprise and seize a drug plane. "It's not like we're some sort of American Rambo."

Torres is temporarily boatless. A 12-foot skiff, half its turquoise paint flecked off to the metal, sits beached beside his stilt-supported command hut. The engine is out for repairs.

But even when it gets back, it won't matter. Their skiff is no match for smugglers' speedboats, which boast more than twice the horsepower of any Peruvian police boat between Santa Rosa and Iqui-tos.

Maranon, interviewed in a grimy-walled precinct office with no panes in its front window, suggested U.S. anti-drug aid be invested less in sophisticated electronics and more in the foot soldiers of the drug war.

"Give the police a commission based on how much coca base (raw cocaine) they seize," he said. "If you pay the people more, they'll move mountains."