More than 2,000 U.S. troops celebrated Valentine’s Day by kicking off Cope North 2018, an annual exercise in Guam, on Wednesday.

The U.S. Air Force, Navy and Marine Corps are joining the Japan Air Self-Defense Force and Royal Australian Air Force to enhance multilateral air operations between the nations, according to an Air Force news release.

The exercise runs through March 2 at Andersen Air Force Base.

The U.S. will train alongside more than 800 Japanese and Australian troops, flying more than 100 aircraft from 21 units.

Troops will practice humanitarian assistance and disaster relief with aerial and force employment events focused on increasing readiness among the three nations, the release said.

The exercise, which began in 1978, used to be held at Misawa Air Base in Japan. In 1999, it moved to Guam.

Andersen Air Force Base hosts the United States’ continuous bomber presence mission, with Air Force bombers — including the B-1B Lancer, B-52 Stratofortress and B-2 Spirit — rotating to Guam.

A U.S. Air Force B-1B bomber, far left, accompanied by South Korea and U.S. fighter jets, flies over the Korean Peninsula Wednesday during a combined aerial exercise. The Guam-based bomber simulated land strikes at a military field near South Korea’s eastern coast. (South Korea Defense Ministry via AP)
A U.S. Air Force B-1B bomber, far left, accompanied by South Korea and U.S. fighter jets, flies over the Korean Peninsula Wednesday during a combined aerial exercise. The Guam-based bomber simulated land strikes at a military field near South Korea’s eastern coast. (South Korea Defense Ministry via AP)

For a few days in January, all three types of bombers flew together for the second time in history. The first time was in August 2016 as part of an historic integrated bomber operation.

Six B-52s and about 300 airmen from Barksdale Air Force Base in Louisiana deployed to Andersen AFB to replace six B-1s from Ellsworth Air Force Base in South Dakota.

Three B-2 stealth bombers and about 200 airmen from Whiteman Air Force Base in Missouri were deployed to Guam as part of the bomber assurance and deterrence mission.

The continuous bomber presence mission has been conducted since 2004 to reassure the United States’ allies in the region and show strength against potential adversaries, including North Korea and China.

The Air Force plans to retire the B-1 and B-2 bomber fleets once the B-21 Raider bomber — which can fly both conventional and nuclear-capable missions — is ready in the mid-2020s.