The black Labrador Retrievers scamper down the street, tails wagging and tongues hanging out.
"Good boy" the officer at the other end of the leash says patting one of the animals on the head. In most ways, these dogs are like any other pet, except these are highly trained military dogs.
In Afghanistan, they searched for explosives, uncovering roadside bombs and improvised explosive devices that likely saved thousands of lives.
"He is a veteran," Officer Anthony Leo explains. "He did two tours in Afghanistan. He was stationed at Camp Leatherneck."
But these days when Yankee goes to work, the four-year-old black lab is fighting the war on terror back at home, as part of the K-9 unit for Metro Transit Police. He searches for explosives in Metro stations and on trains. Officer Leo is Yankee's handler and partner.
"Every day I come to work, I put my life in his hands," said Leo.
Last fall, Metro received nine bomb sniffing dogs from the U.S. Marine Corps. The transit agency won't say if the canines have found anything suspicious in the transit system, but they do have a proven track record in Afghanistan finding IEDs.
"Some of them have superficial wounds all from shrapnel,” said Sgt. Andrew Keahon with Metro Transit Police. “Four of our dogs actually have ear issues because of loud explosions. Two of the dogs specifically cannot hear out of one of their ears as a result of the IED."
When Keahon picked up the dogs in North Carolina, he recalled seeing a wall of photos showing all the dogs and their handlers who died in Iraq and Afghanistan. Some of the Marines relayed stories of how the dogs saved their lives, sometimes multiple times.
One of the dogs with the most finds discovered 32 bombs in Afghanistan.
Keahon recalled one case where a vehicle had stopped at a village and the Marines were getting out to patrol.
"They noticed that when the dog got out of the vehicle, he laid down on the ground which is a positive sign for explosives ... They didn't know they actually stopped right next to an improvised explosive device and the dog saved everyone that got out of that vehicle,” he said.
The dogs adapted easily to Metro. Sometimes the feel of escalators, moving trains and the noise can spook dogs, but not these dogs. The Marine Corps had trained the canines to be acclimated to the explosions and loud noises at war in Afghanistan.
"What we found was when we brought the dogs here to the Metrorail system, that we didn't have any problems ... The loud sounds, the smells, we had none of those issues that we expected because of their training for Afghanistan," Keahon said.
The military has nearly 3,000 active duty canines doing various jobs. The cost can run as high as $40,000 a dog for training and care.
As the U.S. draws down in Afghanistan, some of them were no longer needed, but some of the dogs were only a few years old. Given the steep investment and extensive training, rather than retire the dogs, sending some to police agencies like Metro's was a win-win situation.
"They do police work," Leo said. "He has taught me a lot and I am still learning everyday with him, but I am very lucky to have him."
The Marines trusted their lives to these dogs. Their handlers kept the animals at their side night and day in the war zone and bonded with dogs. So letting go wasn't easy. Before driving away, Keahon said one Marine came to say goodbye. He shook his hand, but held on a little longer than usual and asking the transit police officers to keep a promise.
"When we left them, we promised we would take care of their puppies. And we saw some tears in some eyes when we left," Keahon said.
Metro's officers know these dogs are special and there is pride in knowing these four-legged heroes that protected our men and women at war are now keeping the nation safe on the homefront.