HONG KONG • Vietnam has discreetly fortified several of its islands in the disputed South China Sea with new mobile rocket launchers capable of striking China's runways and military installations across the vital trade route, according to Western officials.
Diplomats and military officers told Reuters that intelligence shows Hanoi has shipped the launchers from the Vietnamese mainland into position on five bases in the Spratly islands in recent months.
The launchers have been hidden from aerial surveillance and have yet to be armed, but could be made operational with rocket artillery rounds within two or three days, according to the three sources.
Vietnam's Foreign Ministry said the information was "inaccurate", without elaborating.
Deputy Defence Minister Nguyen Chi Vinh told Reuters in Singapore in June that Hanoi had no such launchers or weapons ready in the Spratlys, but reserved the right to take any such measures.
The move is designed to counter China's build-up on its seven reclaimed islands in the Spratlys archipelago. Vietnam's military strategists fear the runways, radars and other military installations on those holdings leave Vietnam's southern and island defences vulnerable.
Military analysts say it is the most significant defensive move Vietnam has made on its holdings in the South China Sea in decades.
Hanoi wanted to have the launchers in place as it expected tensions to rise in the wake of the landmark Arbitral Tribunal ruling against China last month in a case brought by the Philippines, foreign envoys said.
The ruling, stridently rejected by Beijing, found no legal basis to China's historic claims to much of the South China Sea. Vietnam, China and Taiwan claim all of the Spratlys while the Philippines, Malaysia and Brunei claim some of the area.
"China's military maintains close surveillance of the situation in the sea and air space around the Spratly Islands," China's Defence Ministry said in a faxed statement to Reuters. "We hope the relevant country can join with China in jointly safeguarding peace and stability in the South China Sea region."
Foreign officials and military analysts believe the launchers form part of Vietnam's state-of-the-art Extra rocket artillery system recently acquired from Israel. Its rounds are highly accurate up to a range of 150km. Operated with targeting drones, they could strike both ships and land targets.
That puts China's 3,000m runways and installations on Subi, Fiery Cross and Mischief Reef within range of many of Vietnam's holdings on 21 islands and reefs.
While Vietnam has larger and longer range Russian coastal defence missiles, the Extra is considered highly mobile and effective against amphibious landings.
"When Vietnam acquired the Extra system, it was always thought that it would be deployed on the Spratlys... it is the perfect weapon for that," said Mr Siemon Wezeman, a senior arms researcher at the Stockholm International Peace Research Institute.
There is no sign the launchers have been recently test-fired or moved.
Mr Carl Thayer, an expert on Vietnam's military at the Australian Defence Force Academy, said the deployment showed the seriousness of Vietnam's determination to militarily deter China as far as possible.
Mr Trevor Hollingsbee, a former naval intelligence analyst with the British Defence Ministry, said he believed the deployment also had a political factor, partly undermining the fear created by the prospect of large Chinese bases deep in maritime South-east Asia.
"It introduces a potential vulnerability where they was none before - it is a sudden new complication in an arena that China was dominating," he said.