The decision to deploy more ships to the Pacific Ocean, along with expanding a network of military partnerships in the region, was part of a "steady, deliberate" effort to bolster the US role in an area deemed vital to America's future, Panetta said.

He said "by 2020, the Navy will re-posture its forces from today's roughly 50-50 percent split between the Pacific and the Atlantic to about a 60-40 split between those oceans including six aircraft carriers, a majority of our cruisers, destroyers, littoral combat Ships, and submarines."

The US Navy currently has a fleet of 285 ships, with about half of those vessels deployed or assigned to the Pacific.

Although the total size of the overall fleet may decline in coming years depending on budget pressures, Pentagon officials said the number of naval ships in the Pacific would rise in absolute terms.

The United States also planned to increase the number of military exercises in the Pacific and to conduct more port visits over a wider area extending to the Indian Ocean.

Panetta was speaking to defence officials from across the region at the Shangri-La security dialogue, a summit organised by the London-based International Institute for Strategic Studies.