Derrek Green's eyes lit up as the black lab galloped across the airport corridor. He bent down, threw his arms out and embraced Zeva, the tail-wagging, retired military dog he had to leave behind two years earlier.

Watching from the side, Molli Oliver's eyes filled with tears. Another happy reunion.

Oliver is a chipper 5-foot-2 flight attendant for United Airlines, who has taken it upon herself to reunite retired military dogs and their former handlers. Her personal mission started last year when she struck up a conversation with a soldier still hurting five years after parting ways with his military canine.

I said, 'Well, where is the dog? I'll get him for you,'" Oliver recalled.

It was the start of a new passion for Oliver. The reunion of Green and Zeva in El Paso, Texas, on Thursday marked her fifth homecoming.

"It was emotional," Green, a 26-year-old Army staff sergeant, said of getting Zeva back. "At one point I almost started crying, but I fought back those tears."

Oliver, 65, of Los Angeles, has always had a deep bond with the military — several members of her family have served. She also has a love for dogs.

She was heartbroken by Sgt. Andrew Mulherron's story as she flew with Marines heading for deployment overseas in April 2015. Mulherron was the first handler for another black lab, Boone, starting in 2009.

Their bond was deepened by the fact that Boone was a hero, receiving a medal for detecting 11 confirmed explosive devices in Afghanistan.

Mulherron eventually settled in California and Boone went to another handler. Oliver tracked down Boone to Fort Leonard Wood, Missouri, and was able to secure permission to fly him to California, her first reunion.

For that one and the next three, Oliver paid for the flights and other costs herself. News about her efforts led to donations, which funded Zeva's trip to El Paso.

Any cost is worth it to see the look on a soldier's face when he has his dog back, Oliver said.

"It's overwhelming for them," she said. "It's a part of them that's been missing."

Doug Miller, working dog manager for the Department of Defense, said the military typically has about 1,700 dogs working in all branches, with another 800 to 1,000 in kennel for training, awaiting assignment, or for medical reasons.

Most dogs are used for patrol and detection of drugs and explosives, Miller said.

Over the course of a dog's working life, the animal typically goes through several handlers. When the dog is retired, the final handler usually gets first dibs. Other times, a past handler has made it clear he or she wants to adopt. If multiple handlers want the dog, the commander chooses "based on the best interest of the dog," Miller said.

Zeva, like Boone, was trained to sniff out bombs. She first teamed with Green in 2013.

It turned out the military had other plans for both of them. Green was sent to a combat engineering unit in 2014. Zeva never really took to the training and remained kenneled in Fort Leonard Wood.

"She definitely is not a military working dog," Green laughed. "She'd rather relax on your couch than go out and look for bombs."

Green, now based in Fort Bliss, Texas, never forgot his friend, and secured permission to adopt Zeva. The kennel master reached out to Oliver.

Last week, she flew to St. Louis and made the 130-mile drive to the Army base to pick up Zeva and fly her to Texas, where the dog now lives with Green, his wife, their three young children and another lab.

Oliver said the first five reunions are only the beginning.

"We're trying to help as many as we can," she said.