On National K-9 Veterans Day, where are military dogs working around the world?

Tuesday is National K-9 Veterans Day, a holiday to honor the dogs who have served the United States in the armed forces, police departments, and other agencies.

Thousands of K-9s serve alongside service members in every branch of the U.S. military all around the world.

ABC News tracked down a few of these honorable dogs to see where they've been training so far in 2018.

Arlington National Cemetery, Virginia

Earlier this month, Reisja, a 7-year-old Belgian Malinois, participated in a simulation of a building "sweep" at Arlington National Cemetery.

"The K-9 Unit conducts sweeps of suspicious packages, vehicles, and buildings to ensure a safe working environment, and in association with high-level threats throughout the National Capital Region," the Army said.

Kadena Air Base, Okinawa, Japan

Bbutler is a Military Working Dog stationed at Kadena Air Base in Okinawa, Japan. Last month, Bbutler participated in counter-narcotics training that utilizes five different narcotic training aides including heroin, marijuana and cocaine.

Bbutler came from Lackland Air Force Base, as evidenced by his unique name. At Lackland, it is standard to double the first letter of a Military Working Dog's name.

Schofield Barracks, Oahu, Hawaii

This dog with the Transportation Security Administration (TSA) completed hidden explosives training during an exercise in Hawaii last month.

"The exercise provided training opportunities for canine handlers with the U.S. Marine Corps, Army, and Navy, as well as Oahu civilian agencies such as the Honolulu Police Department and the Transportation Security Administration," the Department of Defense said. "The exercise also allowed the agencies to cooperate and work through a simulated scenario, producing readiness by strengthening their inter-operability and cohesion."

Fujairah Naval Base, United Arab Emirates

Marine Corps Lance Cpl. Nicholas Hoecker and his dog Argo participated in exercise Native Fury 18 at Fujairah Naval Base in the United Arab Emirates in January.

In this photo, Hoecker was preparing to demonstrate the "five phases of aggression drill" with Argo.