The head of U.S. Pacific Command said today it is “critical” that India’s voice be added to the “chorus of like-minded nations” in the region as China’s actions in the South China Sea increasingly cause worry.

Expanded cooperation with India will not only be the “defining partnership” for the U.S. rebalance to the Pacific, “it will arguably be the defining partnership for America in the 21st Century,” Adm. Harry B. Harris Jr. said in prepared remarks in New Delhi.

Harris, whose headquarters are at Camp H.M. Smith, said he is sometimes asked why he always uses the term Indo-Asia-Pacific rather than Asia-Pacific.

“My answer is simple,” he said. “Indo-Asia-Pacific more accurately captures the fact that the Indian and Pacific oceans are the economic lifeblood that links India, Australia, Asia, Oceania and the United States together.”

On the security front, India is beginning to exert its leadership in the Indo-Asia-Pacific, Harris said, adding: “We are ready for you. We need you.”

India, with the third largest standing army in the world, according to worldatlas.com, is concerned about China’s militarization in the South China Sea and how that could affect its trade routes, as well as Chinese military assistance to Pakistan and Sri Lanka.

But it has been reluctant to take a prominent role in the South China Sea dispute.

“Considering the $5.3 trillion in trade that traverses each year from the Indian Ocean and through the South China Sea, we all have a vested interest in ensuring the entire region remains secure, stable and prosperous.” Harris said. “How Indo-Asia-Pacific nations employ naval forces to support these economic interests matters greatly.”

“By being ambitious,” India, Japan, Australia, the United States and other like-minded nations “can aspire to operate anywhere on the high seas and airspace above them.”

While not mentioning China, Harris’ comments were directed at China’s demands that other nations respect its sovereignty claims to large areas of the South China Sea, which the United States rejects.

The United States wants other nations to conduct freedom of navigation exercises in the waters it believes are international.

“While some countries seek to bully smaller nations through intimidation and coercion, I note with admiration India’s example of peaceful resolution of disputes with your neighbors in the waters of the Indian Ocean,” Harris said.

Harris said an agreement is in place for a series of joint India-U.S. exercises this year. India also will be participating in Rim of the Pacific maritime exercises in Hawaii this summer.

United States offers to provide India Apache attack helicopters, Chinook heavy-lift helicopters and M777 howitzers “are akin to our defense relationships with our closest allies,” Harris noted.