When Pope Francis, leader of the world's estimated 1.2 billion Catholics, visited the U.S. last month, the effort to keep him safe was massive.
It was, according to some experts, the largest security operation in U.S. history.
Among the thousands of law enforcement personnel involved in the pope's security detail were two military working dog teams from Vance Air Force Base.
Staff Sgt. Marshall Rains and his K-9 partner, Rea, and Staff Sgt. Lance Brennan and his dog, Akim, were part of the pope's security detail during his visit to Philadelphia in late September.
Prior to the pope's arrival, both Vance teams swept the areas he would be visiting, looking for anything that could cause him harm. Then, after his arrival, they worked checkpoints checking spectators who were entering secure areas. Just as they do at Vance, the dog teams worked 12-hour days during this assignment.
They did manage to get a glimpse of the pontiff, but only from about 100 yards away.
"You could see him in the Popemobile as he drove though with his motorcade," said Brennan. "He was probably about a good football field away or so."
This was Brennan's first distinguished visitor security detail, but Rains had been in those situations before.
"This was by far the biggest one I've ever been on," Rains said. "It was interesting. It was really a good experience to work with the different agencies that are out there. There were a lot of moving parts, that's for sure."
"This was my my very first one, so the whole traveling process and not being here at home station was different," said Brennan. "The pope is a colossal image for an entire religion. It was cool to see all the effort that went through to keep him secure. Any three-letter agency you can think of was pretty much there."
The two handlers did not travel to Philadelphia together, but took separate commercial flights with their dogs, both German shepherds. Because the airplanes they flew were not large, both dogs rode in the passenger cabin with their handlers. Dogs and handlers train inside large cargo aircraft during their training at Lackland AFB, Texas.
"My pup slept all four flights," said Brennan. "He was nervous while we were at the terminal and once we started to taxi he wanted to go onto the floor and he just slept."
Handlers and their dogs normally are given a row of seats to themselves, but that wasn't the case on this trip.
"Coming back, my last flight from Atlanta to Oklahoma City, I ended up sharing a row with a guy and she (Rea) just ended up laying down over in his foot space," said Rains. "He was OK with it. It's good that people were kind of supportive of the situation."
Brennan and Akim faced a similar situation on their first flight.
"The guy said, 'If the dog's going to lay down, the dog's going to lay down. Who am I to tell a 70-pound German shepherd to get out of my way,'" Brennan said.
And both dogs performed well during their time in Philadelphia.
"He (Akim) was actually very adaptable," said Brennan. "Normally he's kind of jittery and antsy, he seems kind of anxious, and the entire time we were there he was just calm, cool and collected. It was actually really nice."
The dogs stay in the hotel room with their handlers, though they normally sleep in a portable kennel.