Japanese and US military forces are taking part in joint live-fire drills on Japan’s Hokkaido Island in the largest exercises ever held between the two allies.

Service members from Japan’s Self Defense Forces (JSDF) and US Marines Third Division began the drills, dubbed Northern Viper 17 (NV-17), in the Japanese city of Eniwa on Wednesday.

Some 3,500 troops are taking part in the 18-day war games, which will include rocket artillery exercises and other live-fire operations.

A member of the Japanese Ground Self Defense Force stands on a type 90 tank during a joint exercise with US Marine Corps, on August 16, 2017. (Photo by Reuters)

The war games come at a time of tensions between North Korea on the one side and the US, Japan, and South Korea on the other. The US has permanent military presence in the region and routinely engages in joint drills with Pyongyang’s regional adversaries.

“This exercise is extremely important because we have very limited opportunities to come together with our Japanese counterparts in a large scale to conduct this type of training,” said US Marine Corps. Commanding Officer Colonel James Harp.

“We need to continue training like this to better protect the region from its adversaries,” he added.

Soldiers from Japan’s Ground Self-Defense Force take part in a field drill with US Marines during joint military exercises in Eniwa, Hokkaido Prefecture, August 16, 2017. (Photo by AFP)

The NV-17 war games are taking place amid concerns about a potential confrontation between the US and North Korea.

US President Donald Trump threatened last week to unleash on North Korea “fire and fury like the world has never seen” if Pyongyang continued to threaten America.

The remarks initially prompted Pyongyang to announce plans to launch missiles targeting an area near the US Pacific territory of Guam. North Korea, however, later reversed that decision, saying it had postponed the plan to an unspecified future time.

US Marine Corps members launch a mortar during a joint exercise with Japan’s Ground Self Defense Force, August 16, 2017. (Photo by Reuters)

Japan on Saturday deployed some of its land-based missile interceptors, known as Aegis, at its Self Defense Forces (SDF) bases in three of the four prefectures over which any North Korean missiles would likely fly en route to Guam.

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The missile system is reportedly able to track 100 missiles simultaneously and fire interceptors to take out the enemy’s ballistic projectiles.