NEW DELHI (Reuters) - A U.S. aircraft carrier strike group began naval exercises with India and Japan on Monday that the U.S. navy said would help the three countries tackle maritime threats in the Asia-Pacific region.

The Arleigh Burke-class guided-missile destroyer USS Kidd (DDG 100) arrives in India for Malabar July 9, 2017. Mass Communication Specialist 2nd Class Jacob M. Milham/U.S. Navy Photo/Handout via REUTERS

The annual exercises named Malabar are being held off India. They are the largest since India and the United States launched the exercise in 1992. Japan was later included.

“Malabar 2017 is the latest in a continuing series of exercises that has grown in scope and complexity over the years to address the variety of shared threats to maritime security in the Indo-Asia Pacific,” the U.S. Pacific command said.

Military officials say the drills involving the U.S. carrier USS Nimitz, India’s lone carrier Vikramaditya and Japan’s biggest warship, the helicopter carrier Izumo, are aimed at helping to maintain a balance of power in the Asia-Pacific against the rising weight of China.

The three countries have been concerned about China’s claims to almost all of the waters of the South China Sea, and more broadly, its expanding military presence across the region.

Chinese submarines, for example, recently docked in Sri Lanka, an island just off the southern tip of India that it has long seen as squarely in its back yard.

The maritime drills are taking place as India and China are locked in a standoff on their land border in the Himalayas.

The U.S. Pacific command said in a statement the exercises would help the three countries operate together and it was learning how to integrate with the Indian navy.

India and the United States were for decades on opposite sides of a Cold War divide but have in recent years become major defense partners.

China has in the past criticized the exercises as destabilizing to the region.

India this year turned down an Australian request to join the exercises for now, for fear that would antagonize China further.

The Indian navy said the exercises would focus on aircraft carrier operations and ways to hunt submarines.

The navy has spotted more than a dozen Chinese military vessels including submarines in the Indian Ocean over the past two months, media reported days ahead of Malabar.

“Naval co-operation between India, US and Japan epitomizes the strong and resilient relationship between the three democracies,” India’s defense ministry said in a statement.

The border stand-off on a plateau next to the mountainous Indian state of Sikkim, which borders China, has ratcheted up tension between the neighboring giants, who share a 3,500 km (2,175 miles) frontier, large parts of which are disputed.