>>>STATE DEPARTMENT - U.S. officials say shifting more diplomatic, commercial, and military assets to the Asia-Pacific region is not a threat to China.

Stepped-up Chinese naval exercises are partly a response to the Obama administration's diplomatic and military rebalance to Asia. But U.S. officials say it's not about confrontation, it's about stability.

"In this respect, the success of the rebalance hinges on having a positive and productive relationship with China. So absolutely the rebalance is not about China. What China does, though, of necessity does impact how we think about the region," said David Helvey, Deputy Assistant Secretary of Defense for East Asia.

With growing threats from North Korea, the United States must continue to reassure its allies, says George Mason University professor Janine Davidson. "As tensions rise on the Korean peninsula or in the South China Sea, the reaffirmation of this security guarantee can prevent a destabilizing arms race among nervous countries in the region," he stated.

Critics say the Obama administration is mishandling threats. Republican Senator Marco Rubio. "Our allies in the region want to make sure that not only are we saying these things," he explained. "But we are actually in a position to do something about these security commitments.

With rival claims over lucrative oil and fishing rights in the South China Sea, it's a question of managing resources, said Acting U.S. Assistant Secretary for East Asia Joseph Yun. "There are no resolutions. Nobody's ever going to give up their claims. So really the question is: how do you manage it? One of the models of managing is through joint use, joint exploration, joint agreement," he stated.

U.S. Secretary of State John Kerry has been trying to manage some of that cooperation and reassure Chinese officials, among them the new premier Li Keqiang. "Our common interests are far more than our disputes. As big countries, we have a responsibility to maintain the peace and stability of the region," Li said.

But it is because of China that nearly all U.S. allies in the region want greater security cooperation, says Georgetown University professor Michael Green. "Many of them trade more with China than they do with us -- including Japan, Korea, Australia, three of our most important allies -- and so none of them wants to be ever put in a position where they have to choose between Washington and Beijing," Green noted.

Green believes Beijing now sees its own actions as part of the reason why neighbors want greater U.S. involvement. "The Chinese side will continue to argue it is containment, but I think they have drawn the lesson. They imposed a self-inflicted wound, an on-side goal in 2010 by pushing their neighbors closer to us," he said.

Washington says it will remain a Pacific power that is committed to working with China on regional issues such as North Korea and on broader goals such as curtailing Iran's nuclear program.