US Secretary of Defense Ashton Carter headed Saturday to India and the Philippines for talks on increasing regional defense cooperation, after calling off a planned trip to China amid tensions over Beijing's expansionist ambitions in the South China Sea.

Carter will fly out of Washington and travel to India and the Philippines for his Asian tour, followed by Middle East stops in the United Arab Emirates and Saudi Arabia.

China lays claim to almost all of the contested South China Sea, which is important for international shipping and is believed to hold valuable mineral and energy deposits.

Neighboring countries and Washington fear China could impose military controls over the entire South China Sea, and Beijing has in recent months built massive structures including radar systems and an airstrip over reefs and outcrops.

The Philippines is among several other regional countries that also have claims to the strategic zone.

"Almost all the nations there are asking us to do more with them... bilaterally and multilaterally," Carter told the Council on Foreign Relations think tank in New York on Friday.

"Many of those countries are reaching out anew to the United States to uphold the rules and principles that have allowed the region to thrive."

In India, where Carter will stay through Wednesday, he will discuss new partnerships and modernizing old alliances, according to the Pentagon.

"We are now doing things that could not have been imagined 10 years ago," a senior US defense official said.

- Fighter jets -

The United States and India are cooperating in aircraft carrier design, jet engine technology, and may collaborate on jointly producing jet fighters.

On the military side, India is again participating in the US-led Red Flag advanced aerial combat training exercise, and recently joined US and Japanese forces in an anti-submarine and air defense exercise.

Aside from meeting Prime Minister Narendra Modi and his counterpart Manohar Parrikar, Carter is scheduled to visit the Vikramaditya, one of two Indian aircraft carriers.

The Vikramaditya formerly belonged to the Soviet Union's navy, and entered the Indian navy in 2013.

In the Philippines, Carter will visit the Antonio Batista Air Base on the island of Palawan, which faces the South China Sea and the islands claimed by Beijing.

The Philippine base is part of five that the US army can use to temporarily rotate soldiers, following a military cooperation agreement that came into effect in January.

- No stop in China -

Access to the five bases will "enhance our ability to operate within the Philippines... and in South China Sea -- and of course, reinforce our deterrent message," a senior defense official said.

The agreement marks a return of US military to the Philippines, which was a US colony from 1898 to 1946. Until 1992 the Philippines was also home to Subic Bay naval base and Clark Air Base, two of the largest US military bases abroad.

During the visit Carter is scheduled to meet Philippine President Benigno Aquino and Defense Secretary Voltaire Gasmin.

Carter, however, chose to not stop in China during his Asian tour, even though he had earlier accepted an invitation to visit.

The decision to skip China was made just a few weeks ago, highlighting tensions between Beijing and Washington over the South China Sea.

Carter "did officially accept an invitation to travel to China in spring," said Pentagon spokesman Bill Urban. However, "scheduling problems" prevented that visit from happening.

"We are actively looking" for another date to visit "this year," Urban said.

Carter leaves Asia on Saturday and heads to the United Arab Emirates and Saudi Arabia, where among other things he will participate in a Gulf Cooperation Council ministerial meeting ahead of a GCC summit that will include President Barack Obama.