YOKOSUKA NAVAL BASE, Japan — Last summer, Olli the drug dog sat down with ears pointed, awaiting his toy — his signal to his handler that he’d just done his job.

Inside the vehicle he’d just inspected was $1.5 million worth of the drug known as Ecstasy.

It was a rare bust, handlers said, but one that exemplified the role of the Navy’s working dogs. They’re trained to detect microscopic amounts of drugs or explosives, depending on the dog, in a ship, building, car or even outdoor park, said Yokosuka’s kennel master, Petty Officer 1st Class Marcus K. Watkins, a master-at-arms.

The dogs can detect marijuana, hashish, Ecstasy, methamphetamines, cocaine and heroin. They work solely for praise and reward.

Before a search at a barracks recently, Olli’s tail was wagging and his eyes were bright.

“He wants to find something to get his toy,” said Petty Officer 2nd Class Patrick Dunn, Olli’s handler. Olli got the toy — even though the only drugs found at the barracks that day were the ones planted there for training.

The dogs are tested all the time, using drugs the security office ordered from a U.S. lab.

When they find the drugs, which they must do at least nine times out of 10 to stay certified, the dogs sit and wait for their tug toy, ball or treat.

The canines also are trained to stop fleeing suspects. But people seldom run when the threat of a dog comes into play, Watkins said.

“Usually, they give up. Nobody likes a dog bite.”

Fleeing suspects and drug users are rare at Yokosuka, but the dogs serve an important role, he said. Most Yokosuka drug busts stem from urinalysis, not detection by dogs. That indicates most drug users probably don’t deal them or keep a stash on base, Watkins said: “The sailors see us coming all the time. That’s a great deterrent.”

The dogs can sniff out the smallest speck of drug material and even residual odors. Watkins recalled a drug sweep outside a club in San Diego in which his dog uncovered a few marijuana seeds and the tiny tip of a joint inside a vehicle.

“It can be a marijuana seed in your rack, but that thing exudes a lot of odor,” he said. “And the MWD (military working dog) is going to detect it.”

The dogs work wherever the Navy is — at the New Sanno Hotel in Tokyo and aboard all the ships. The latter takes unique skills for the canines, including riding in small inflatable boats, being hoisted up to ships in a harness and climbing up and down the ladders between decks.

The kennel obstacle course where the dogs live simulates all kinds of environments, trainers said. The dogs even learn to wear goggles — called “doggles” — to protect their eyes during work in the desert.

The handlers say working in Yokosuka means fewer busts than at bigger bases such as San Diego, but even with few cases they stay busy maintaining a presence.

“We’re not trying to ruin anybody’s career,” Watkins said. “We’re here to do deterrence, to enforce the Navy’s zero-tolerance policy” against drugs.