By Greg Torode
ABOARD THE USS GEORGE WASHINGTON, South China Sea (Reuters) - While cuts in Pentagon budgets and political gridlock in Washington have cast doubt on the sustainability of a U.S. "pivot" back to Asia, its military realities are all too clear from the flight deck of the USS George Washington aircraft carrier.
F-18 Super Hornet jet fighters roar from its decks with chest-thumping velocity less than 300 km (185 miles) from the Chinese coast - a symbol of U.S. naval dominance in Asia that Chinese analysts fear could contain Beijing's rising power for decades.
Yet just 30 km (19 miles) away is a lone Chinese naval frigate, well within the protective screen of U.S. ships and aircraft that protect the carrier across a vast swathe of the disputed South China Sea.
The officers of the Washington are hosting People's Liberation Army officers on-board as part of efforts to engage a Chinese military wary of being contained by U.S. forces across Asia. The frigate has not been invited.
The Washington strike group commander, Rear Admiral Mark Montgomery, stretches his arm to the left horizon where the frigate is obscured by haze and acknowledges such encounters by the rival powers are now more common.
"You can definitely see the Chinese navy is modernizing and expanding," he said. "It would be a natural conclusion they would be operating in the vicinity of us."
Montgomery said routine communication with Chinese naval ships was "professional" and that the U.S. navy was determined to aid the long-troubled relationship with "transparency and openness".
"I don't have any issues with them operating in the vicinity of our ships," he said.
The Washington strike group - that often includes destroyers, cruisers and a fast-attack submarine backed by up to 90 aircraft - protects the only one of 10 carriers deployed permanently outside the continental United States.
Based in Yokosuka, Japan, the Washington is the most visible sign of an increased U.S. naval presence across Asia that has been steadily growing for the last five years - a key element in the controversial U.S. "pivot".
On Friday, it is due to arrive in the financial hub of Hong Kong after months across the region running joint exercises, maneuvers and training.
While U.S. military brass attempt to ease China's fears that the United States is determined to hem China in, as it re-engages the region, its old allies and newer friends are wanting reassurances the United States is going to stay around.
Last month, U.S. President Barack Obama said China had probably taken advantage of his absence from two summits in Asia which he could not attend because of the partial U.S. government shutdown and fiscal debate.
The presence of the strike group in the South China Sea appears geared to addressing the core of U.S. engagement in the region. The overlapping claims of China, Taiwan, the Philippines, Vietnam, Brunei and Malaysia in the oil- and gas-rich sea is emerging as a regional flashpoint.
The United States has said it is neutral in the dispute - centered on China's controversial historic claim of waters deep in the maritime heart of Southeast Asia - but is determined to preserve peace and ensure that sea-lanes vital for the world economy are not hindered.
Even as it grapples with budget cuts, over the next few years the United States will significantly expand joint exercises, live-firing tests and anti-submarine drills in the region, in part to cope with advancing Chinese weaponry, according to the Stars and Stripes, the U.S. military newspaper.
And on board the George Washington, officers and crew say combat readiness is being maintained through costly flight schedules that see 100 sorties routinely flown from the ship on most days.
Chinese officials and commentators often bristle at the U.S. efforts. Despite years of double-digit increases in defense spending by China, it lags far behind the United States in terms of firepower.
Chinese pilots are still testing landings aboard the Liaoning, a Soviet-era ship that has been re-tooled as China's first aircraft carrier.
China's first domestically built carriers are not expected to be completed before 2020, according to military analysts, even as its shipyards produce new nuclear and conventional submarines, destroyers and other heavily armed surface ships faster than any other nation.
Its expanding fleet has started routinely exercising far beyond China's coastal waters, moving beyond the so-called first island chain that has long effectively contained China's navy and into open ocean east of Japan.
Both Asian and Western analysts, however, believe China's navy would struggle for some years to sustain protracted battles far from its shores.
Assessing the situation from the bridge, high above the flight deck, Montgomery insists his navy is committed, both in terms of operational capabilities and engagement.
Put simply, he says: "There are more ships involved here."
(Editing by Robert Birsel)