The United States will renew its naval power across the Asia-Pacific region and stay "vigilant" in the face of China's growing military, Defense Secretary Leon Panetta said Tuesday.

On the eve of a trip to Asia that will include stops in Singapore, Vietnam and India, Panetta said in a speech that the country's future depended on ensuring security throughout the Western Pacific and the Indian Ocean.

"America is a maritime nation, and we are returning to our maritime roots," Panetta told graduates of the US Naval Academy in Annapolis, Maryland.

"One of the key projects that your generation will have to face is sustaining and enhancing American strength across the great maritime region of the Asia-Pacific," he said.

Reflecting US concern over China's rise and more assertive stance in the South China Sea, President Barack Obama has announced a strategic shift toward Asia after wrapping up the US military presence in Iraq and overseeing a troop drawdown in Afghanistan.

Panetta encouraged the new naval officers to forge stronger security ties with China even as he vowed the United States would not let down its guard.

"We need you to strengthen defense ties with China. China's military is growing and modernizing. We must be vigilant. We must be strong. We must be prepared to confront any challenge," he said.

"But the key to that region is to develop a new era of defense cooperation between our countries -- one in which our militaries share security burdens in order to advance peace in the Asia-Pacific and around the world," he said.

He called on the graduates to strengthen longtime alliances with Japan, South Korea, Australia and the Philippines while also building "robust partnerships" with countries such as Malaysia, Indonesia, Vietnam, Singapore and India.

In Singapore this week, Panetta is due to attend an annual Asia security summit, the Shangri-La Dialogue, organized by the London-based International Institute for Strategic Studies.