That dispute reached a fever pitch this summer when Chinese authorities started moving an offshore drilling rig around the area for exploratory drilling; resulting in widespread anti-China riots and protests in Vietnam, including one self-immolation. More recently, senior Vietnamese officials visited China, and were able to carve out an agreement about a future dispute resolution mechanism.
Vietnam, meanwhile, isn't apparently going to file this under "No harm, no foul" and is instead continuing with plans to arm up, just in case. This November, Vietnam will be receiving a delivery of an Improved Kilo-class submarine, the third in a package of six that it purchased from Russia in 2009. Vietnam signed the 2009 agreement around the same time as China's announcement of the nine-dash line, in which China laid claim to 80 percent of the South China Sea.
These subs are very roughly comparable (or a bit better) than the Kilo submarines China has in its inventory. To help Vietnam make better use of their newly-purchased submarines and payload of new Klub submarine-launched anti-ship missiles, India agreed last year to train 500 Vietnamese sailors.
This cooperation between Vietnam, Russia, and India extends into other domains as well. In August, Vietnam also purchased another 12 Su-30MK2 fighters — a long-range, maritime strike aircraft — and hopes to have 36 of the aircraft deployed by 2015. India and Vietnam are expected to sign an agreement when Indian President Pranab Mukherjee visits next week that will include Indian training for Vietnamese Su-30 pilots. India already operates a Su-30 variant, and has been building increasingly close ties with Vietnam as part of its Look East policy.
Beyond the deal to train pilots, Vietnam may also sign agreement for the purchase of BrahMos supersonic anti-ship missiles. The BrahMos missile is the product of a Russian-Indian joint venture and has a claimed speed of Mach 3.0+ and a range of more than 180 miles. The missile is one of the fastest anti-ship missiles made and a significant anti-ship cruise missile threat, able to reach targets well into the South China Sea.
India has been on the fence about exporting these missiles to Vietnam, mindful of its relationship with China, but an unnamed source in an article by the Russia&India Report noted "We understand their concerns, but then China is not ready to appreciate our concerns about the threat from Pakistan."
Altogether, these submarines, Sukhoi fighter jets, and supersonic cruise missiles have the makings of a very effective deterrent threat and Anti-Access/Area-Denial (or A2/AD) strategy for Vietnam. A2/AD strategies are intended to prevent navies from projecting power into an area, and came into the spotlight in the defense community a few years ago, when China shifted to such an approach to deny the US access to the Western Pacific.
Now it seems that India is willing to consider putting the screws to China on its disputes with Vietnam, as long as China seems unwilling to help India in their territorial disputes with Pakistan. Meanwhile, Russia seems content to arm the Vietnamese, perhaps reasoning that denying Chinese access to South China Sea energy resources will make them a lucrative market for Russian energy firms.
Of course, none of these moves are in isolation. Other nations in the region, such as Indonesia, are interested in purchasing BrahMos missiles. Japan has been working to build ties with India, Vietnam, the Philippines, and other countries. The US is edging closer to establishing tighter ties with Vietnam as it works to build a tighter relationship with China. There's no guessing where everything will land once the music stops, but it seems that Vietnam is going to try to weather this by speaking softly and carrying a big stick.