Vietnam will soon have a credible naval deterrent to China in the South China Sea in the form of Kilo-class submarines from Russia, which experts say could make Beijing think twice before pushing its much smaller neighbor around in disputed waters.
A master of guerrilla warfare, Vietnam has taken possession of two of the state-of-the-art submarines and will get a third in November under a $2.6 billion deal agreed with Moscow in 2009. A final three are scheduled to be delivered within two years.
While communist parties rule both Vietnam and China and annual trade has risen to $50 billion, Hanoi has long been wary of China, especially over Beijing's claims to most of the potentially energy-rich South China Sea. Beijing's placement of an oil rig in waters claimed by Vietnam earlier this year infuriated Hanoi but the coastguard vessels it dispatched to the platform were always chased off by larger Chinese boats.
The Vietnamese are likely to run so-called area denial operations off its coast and around its military bases in the Spratly island chain of the South China Sea once the submarines are fully operational, experts said.
That would complicate Chinese calculations over any military move against Vietnamese holdings in the Spratlys or in the event of an armed clash over disputed oil fields, even though China has a much larger navy, including a fleet of 70 submarines, they added.
"Sea denial means creating a psychological deterrent by making sure a stronger naval rival never really knows where your subs might be," said Collin Koh of Singapore's S. Rajaratnam School of International Studies.
"It is classic asymmetric warfare utilized by the weak against the strong and something I think the Vietnamese understand very well. The question is whether they can perfect it in the underwater dimension."