WASHINGTON — The first year for the military exercise Defender Pacific will be smaller in size than its sister drill in Europe in 2020, but it will still be one of the largest exercises conducted by the U.S. Army and its partners and allies in the region since Team Spirit drills in South Korea ended in the early 1990s, according to acting U.S. Army Pacific Commander Lt. Gen. John “Pete” Johnson.

The Army will flow roughly 12,000 soldiers into the region next year around September for the exercise, Johnson told Defense News in an interview ahead of the Association of the U.S. Army’s annual conference.

The exercise is fueled by a rising China, characterized in the National Defense Strategy as a long-term, strategic competitor of the United States. The NDS lays out a world where great power competition rather than counterterrorism will drive the Defense Department’s decision-making and force structure.

While the U.S. Army has 85,000 permanently stationed troops in the Indo-Pacific region and is conducting exercises such as Pacific Pathways with allies and partners, the service is aiming to practice rapid deployment from the continental United States to the Pacific.

“We’re clearly doing it to demonstrate our commitment to the region and reinforce each of our bilateral relationships,” Johnson said. “We’re also doing it to train ourselves, increase our ability.”

Exercise elements could include humanitarian assistance, disaster relief or address a range of security concerns the U.S. might have, Johnson said.

Before retiring, the former U.S. Army Pacific Command chief, Gen. Robert Brown, told Defense News that the major exercise would focus on a South China Sea scenario.

“They will get the challenge of coming to the Pacific with the Pacific-assigned forces already there,” Brown said, “and we won’t go to Korea, we will actually go to a South China Sea scenario where we will be around the South China Sea; and another scenario we can do that is the East China Sea.”

The South China Sea has been a hotbed of contention for several years. China has laid claim to the area, building artificial islands in disputed waters with military facilities on them, with the country claiming it has the authority to restrict international navigation.

But Johnson made it clear that while aspects of the exercise might take place within the bounds of the South China Sea area, “this is not a war game. We’re not doing a war game with our bilateral partners,” he said, “We’re simply trying to make sure that if we had to come to their assistance in that part of the region, that we certainly can. We’ve got to understand the environment, we’ve got to understand the constraints, the challenges, and we’ve worked through them.”

The exercise will consist of many things the Army has not practiced at such a large scale. Forces will be in countries like the Philippines and Thailand, and they will likely work with other countries like Malaysia, Indonesia and Brunei.

The Army also plans to conduct parts of the exercise with other partners “like our compact states, Papua New Guinea, etc.” to deliver the force forward, Johnson said. The compact states consist of the Federated States of Micronesia, the Marshall Islands and Palau.

The exercise will aim to challenge the U.S. in its ability to deploy from the continental U.S., Johnson said. “The tyranny of distance is real from the continental United States into this region, and it takes a tremendous amount of effort to do that.”

Defender Pacific “will go a long way to enable our joint logistics enterprise, to itself, and for us to train on those key force projection tasks to be able to flow forces into theater,” he said, “ and then once into theater, we’re essentially connecting to our existing bilateral relationships.”

Forces on the ground are expected to execute missions and train with allies. The Army rescheduled some exercises traditionally held during different times of the year to fall under Defender Pacific “so that we can get the stressor, the simultaneity, and we get the stressor on our joint logistics,” Johnson said.

Adding in elements of Mutli-Domain Operations, the service’s war-fighting concept, a multidomain task force will be integrated into the exercise.

While Defender Pacific in 2020 will be smaller in troop count — a “light” version — as Johnson called it, the exercise the following year will be much larger — the “heavy” version.

Defender Europe will be larger this year but will trade off in size with the Pacific as the Defender series become annual, Johnson explained. It’s possible the Defender series might even have elements in the homeland, he added.

In 2021, Defender Pacific is preparing to involve roughly 30,000 troops in the region, Johnson said.