He attended the 15th Shangri-La Dialogue (SLD) convened in Singapore, which provided much food for thought as he headed for Hanoi.

The annual SLD gives a window seat on the US's rebalance in Asia and the tensions in South China Sea. What struck Parrikar, though, would have been two things.

One, aside the inevitable sparring between the US Defense Secretary Ashton Carter and the deputy chief of the Chinese military's Joint Staff Department Admiral Sun Jianguo, the Pentagon chief overall adopted a soft tone.

He even made a distinction between the South China Sea issues and the US-China relationship and Asia-Pacific security.

Carter acknowledged that Washington and Beijing shared views on many global issues and had commonality of interests and he talked about cooperation with China and other countries.

This was not what Parrikar probably would have expected to hear.

Secondly, the Chinese and Vietnamese military delegations sought each other out for a 'bilateral' on the sidelines of the SLD, which, again, underscored that the verve of the Vietnam-India relationship would depend to a large extent on what China does.

Beijing enjoys political similarities and a historical comradeship with Hanoi. The two communist regimes have a shared interest to push back at the US' attempts to erode their political system.

China pursues a hard-nosed strategy against Vietnam in the South China Sea and it is much stronger militarily. But a conflict is the last thing Vietnam wants. On the other hand, a Chinese attack on Vietnam across the land border is highly improbable.

Unless these strategic parameters change dramatically or fundamentally, Vietnam is unlikely to seek a sea change in the relationship with China, which also happens to be hugely consequential to Hanoi in economic terms.

As Parrikar left Delhi, there was much media hype that India was, finally, crossing the Rubicon to sell the BrahMos supersonic missile to Vietnam.

BrahMos is a short-range ramjet supersonic cruise missile that can be launched from submarines, ships, aircraft or land. The missile system hascaught the attention of a number of countries in Latin America besides South Africa, as it has been developed at a low budget of $300 million.

Vietnam first notified its interest to procure BrahMos supersonic missiles from India in 2011. But India parried. Today, however, the two ostensible hurdles are no longer there.

Just last week India became a member of the Missile Technology Control Regime, which now entitles it to sell missile technology to other countries.

Again, New Delhi and Moscow agreed 'in principle' recently to export Brahmos missiles to third countries. (BrahMos is a joint venture between Russia's NPO Mashinostroeyenia and India's Defence Research and Development Organisation.)

However, there has all along been a third factor China had voiced disquiet about the transfer to Vietnam of BrahMos, which holds the potential to shift the balance of power in the South China Sea. BrahMos is one of the deadliest anti-ship missiles in the market.

Now, Russia's consent is needed before India transfers the missile to Vietnam. And Moscow finds itself between the rock and a hard place.

New Delhi takes the line that BrahMos can be exported to countries that are friendly toward both India and Russia. Moscow concurs.

But then, what if the arms deal hurts the security interests of a fourth country that has very close relations with either India or Russia in this case, China?

There are no easy answers. In a somewhat comparable situation, Moscow respects Indian sensitivities over the transfer of advanced weapon systems to Pakistan.

BrahMos becomes a test case of the 3-way equations involving India, Russia and China, three countries that co-habitate BRICS and Shanghai Cooperation Organization.

Russia enjoys very good relations with China. It needs to figure out how to be party to an arms deal that could hurt its ally's interests in South China Sea.

Interestingly, Parrikar also witnessed on the sidelines of the SLD at Singapore a meeting between Russian Deputy Defense Minister Anatoly Antonov and China's Admiral Sun. Antonov was quoted as saying,

Only a week ago, while addressing an international conference in Moscow, Russian Foreign Minister Sergey Lavrov also said,

To be sure, the complicated regional milieu ensuing from the US' rebalance in Asia and the backdrop of the New Cold War have led to the Sino-Russian entente and the two big powers coordinate their regional policies to an unprecedented degree.

Unsurprisingly, Russia avoids commenting on the discussions regarding the possible sale of BrahMos by India to Vietnam. But, conceivably, it has had confidential exchanges with India.

India, of course, is the number one buyer of Russian weapons. Russia is also Vietnam's principal supplier of weapons traditionally. Of late, Russia has begun supplying advanced weapon systems to China such as the S-400 missiles.

Clearly, Russia is the big dad here. But Russia will not be prescriptive toward India. Moscow will expect New Delhi to get the sense of its high sensitivity over an action by its close Indian friend that might affect Chinese interests in South China Sea.

This is a new role that Russia is called upon to play. At the recent annual meeting of the Russia-India-China forum at foreign-minister level held in Moscow, Russia steered a consensus on the South China Sea.

It was a signal victory for Russian diplomacy that the three countries agreed to hold discussions later this year on the South China Sea situation.

Suffice it to say, if India exercises self-restraint on the sale of BrahMos missiles to Vietnam, credit goes to the resilience of India-Russia strategic understanding.

A detailed press release by the Indian Defense Ministry on Parrikar's talks in Hanoi said the two defense ministers 'reviewed the entire spectrum of defense cooperation initiatives between the two countries and focused on measures to further strengthen their bilateral defense relations'.

Parrikar 'emphasised the need for greater defense industry cooperation (and) on enhancing the defence industry networking, information sharing and exploration of possibilities for partnerships and collaborations between the two countries'.

The two ministers touched on cooperation in maritime issues relating to 'the necessity for sharing of white shipping information to facilitate exchange of information in the maritime domain (and) on enhancing hydrographic cooperation'.

But the Indian statement says not a word about BrahMos missile or South China Sea or regional situation. It highlighted that Parrikar's talks related exclusively to bilateral cooperation.

Ambassador MK Bhadrakumarserved as a career diplomat in the Indian Foreign Service for over 29 years, with postings including India's ambassador to Uzbekistan (1995-1998) and to Turkey (1998-2001). He writes the 'Indian Punchline' blog and has written regularly for Asia Times since 2001.

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