The United States' pivot to Asia will not mean any new bases in the region, but existing alliances will be strengthened and modernised, the chief of US Pacific Command (PACOM) told reporters Friday.

"The US has no intention of establishing more bases" in Asia, Admiral Samuel Locklear told reporters in a telephone news conference from PACOM headquarters in Hawaii.

"What we hope to do with our partners... is to continue to operate closely," he said, adding "this part of the world has been pretty safe" in the past 60 years.

The comments came as Washington increases military exercises with allies and gradually moves its most advanced ships, weaponry and aircraft to Asia as part of a long-term strategy.

The shift comes as several Asian countries face friction with China over disputed territory and borders in the East China Sea and the South China Sea.

"There has been significant speculation, scepticism about the US rebalance towards the Asia Pacific region. Let me just say this: The rebalance is a strategy of collaboration and cooperation," Locklear said.

"And the keystone of our rebalance will be... the strategy to modernise and strengthen our five Pacific treaty alliances," he said.

He also said Australia is "a critical pillar" in the US rebalance and that the Asia-Pacific region cannot be considered in isolation from the Indian Ocean, while welcoming New Delhi's role in building security networks.

"There is no simple answer to one security organisation that will work" like NATO in Europe, because the region "is too diverse", he said.

"So the model that -- sometimes people ask me like this 'why don't you have a NATO in the Indo-Asia-Pacific?' -- I served in NATO before, it's a fun organisation but I don't see a parallel here," he said.

"I'd rather (see) what I refer to as a patchwork of security relationships in various parts of this vast region that work together to be able to sense and understand where the security moment is, and to work together to ensure the (security) environment is strong enough to withstand any shocks.

"India is taking a leadership role in working to build some of these security networks, and we welcome that," he said.

Asked about the ongoing tensions between China and Japan over territorial claims to a set of islands in the East China Sea, Locklear repeated that the US did not take a position on the archipelago's final sovereignty.

"What we do expect is these disputes will be done in a fashion without coercion, and that ultimately will be satisfying and decided between governments and without military interventions."

In the wider Asia-Pacific region, he said it was important to build "a code of conduct" in waters that every country, including China, will be obliged to follow.

He also noted the United States is encouraging the nations that have territorial disputes in the South China Sea and the East China Sea "not to introduce military hardware aspects that could lead to miscalculation".

Japan and China have repeatedly butted diplomatic heads over who owns Tokyo-controlled islands called the Senkakus in Japan and the Diaoyus in China. Beijing separately has disputes with other regional capitals, including Manila and Hanoi.