By Greg Torode and Megha Rajagopalan
HONG KONG/BEIJING, Aug 29 (Reuters) - One Chinese naval officer has advice for fighter pilots intercepting U.S. surveillance planes in the wake of an incident over the South China Sea last week that Washington condemned as dangerous - fly even closer.
The comments by Rear Admiral Zhang Zhaozhong from the National Defense University in Beijing, reported in state media this week, reflect what Chinese military experts say is China's determination to shield its expanding ballistic missile submarine fleet from U.S. spy planes.
Risky intercepts off China's coast are likely to continue, even intensify, the experts said, adding that such actions could represent a directive from above rather than the actions of rogue pilots.
"We didn't give them enough pressure (before)," Zhang said in the Global Times, a popular tabloid under the official People's Daily newspaper that is known for its nationalist sentiments. "A knife at the throat is the only deterrence. From now on, we must fly even closer to U.S. surveillance aircraft."
Pentagon officials said a Chinese fighter buzzed a P-8 Poseidon anti-submarine and reconnaissance plane on Aug. 19, at one point flying 9 metres (30 feet) from its wing tip before doing a barrel role over the top of it.
China dismissed the criticism as groundless and said the pilot had kept a safe distance.
A likely target of the U.S. surveillance is China's submarine fleet operating from a base in southern Hainan island, the military experts said.
Among the submarines using the base are large Jin-class vessels capable of carrying nuclear-armed ballistic missiles that are expected to form a key plank in China's nuclear deterrence strategy.
The precise operational readiness of China's three or four Jin-class vessels, including their missile launching capabilities, is not publicly known, military analysts said.
"Long-term, these submarines are China's only hope for a meaningful deterrence ... they are everything to China," said Zhang Baohui, a mainland security specialist at Hong Kong's Lingnan University and author of a forthcoming book on Beijing's nuclear strategy and forces.
Ballistic missile submarines are more important to China's nuclear deterrent than other major powers due to Beijing's policy, dating back to the 1960s, of not deploying nuclear weapons unless attacked with them first, he said.
This means China's larger land-based missiles are considered vulnerable to a first strike if Beijing fulfills its "no first strike" pledge during a conflict.
Having submarines able to travel far into the Pacific Ocean undetected with missiles that can reach the United States was therefore China's "only hope of a credible nuclear deterrent, as it secures second strike capability", Zhang added.
"Their deployment will, of course, complicate U.S. strategic calculations - and we may already be seeing the impact of that," Zhang said.
The P-8 Poseidon was southeast of Hainan in international airspace when it was intercepted.
A U.S. defence official said the Chinese pilot was from the same Hainan unit that appeared to be responsible for other encounters in March, April and May, part of what he called a rising trend of "nonstandard, unprofessional and unsafe" intercepts of U.S. aircraft since the end of 2013.
Six state-of-the-art P-8s were deployed to Okinawa in Japan starting late last year, replacing Cold War-era EP-3 aircraft.
Within Asian and Western military circles there is much debate about the skill and discipline of Chinese pilots.
One retired Chinese military officer, speaking to Reuters, countered that standards were "very high".
Sending Chinese fighters out to "drive away" U.S. surveillance planes was an effective tactic, said Wang Yanan, a military analyst and a senior editor at China's Aerospace Knowledge magazine.
Over time, the U.S. military might reduce the frequency of its surveillance missions, Wang told the Global Times.
Added Zhang, the security specialist: "These are not rogue pilots. I believe we will continue to see them challenging U.S. surveillance planes at very close range as a concerted effort."
A senior U.S. official in Washington said the Obama administration was unclear on how far up China's chain of command authorisation may have been given for the aggressive flying or whether local commanders or pilots were acting on their own.
U.S. and Chinese military officials have been holding talks in Washington this week on rules of behaviour. While the discussions were planned before the latest incident, they touch on issues at the core of U.S. concerns: that a Chinese provocation could spiral into a broader crisis.
Tokyo has also criticised similar flying by Chinese pilots in a controversial Air Defence Identification Zone that Beijing created over the East China Sea last November.
Japan scrambled fighter jets against Chinese planes 104 times in the April-June period, up 51 percent on the year but down from 128 scrambles in the previous quarter.
Taiwan said on Tuesday it had sent jets to intercept two Chinese military aircraft which breached its airspace four times on Monday. China said it was a routine mission.
A report in the Global Times claimed the P-8 had dropped a sonar buoy from its undercarriage, triggering the interception.
Indeed, surveillance by the United States was seriously damaging to China's security, Yang Yujun, a spokesman for the Ministry of Defence, said in a statement on Thursday.
Chinese media and Western military blogs have shown photographs in recent months of Jin-class submarines operating from the Hainan naval base, which includes hidden submarine berths built into a mountainside.
The submarines are eventually expected to be based permanently in Hainan, given its proximity to deep-water channels leading into the western Pacific.
Admiral Samuel Locklear, commander of the U.S. Pacific Command, said in March that China was continuing to produce submarines to be equipped with new missiles that had a range of more than 4,000 nautical miles.
China has 70 submarines, the United States 72 and Japan 18, according to The Military Balance 2014, a publication from the London-based International Institute for Strategic Studies.
"This will give China its first credible sea-based nuclear deterrent, probably before the end of 2014," Locklear said.
Those comments sparked debate among military experts about the effectiveness of the Jin-class, given reports they are noisy and thus easy to find. They are expected to be eventually replaced with a new generation of submarine.
P-8s routinely perform a range of maritime intelligence tasks that are part of a vast U.S. surveillance web across East Asia that includes satellites, undersea sensors, surface ships and nuclear-powered submarines the Pentagon bases in Guam.
The relatively shallow waters of the South China Sea are tricky operating conditions for U.S. submarines seeking to track rival vessels, putting extra importance on the P-8, said Asian and Western diplomats and military experts.
When asked if the United States would reduce surveillance flights to help the military relationship with China, Pentagon spokesman John Kirby said current operations would continue along with efforts to build ties, without providing detail. (Additional reporting by Matt Spetalnick, David Brunnstrom and Phil Stewart in Washington and Kiyoshi Takenaka in Tokyo; Editing by Dean Yates)