To get a clearer understanding of the remarkable events that took place in Hanoi early this week, casual observers must acquaint themselves with that name.

It represented the shock that Vietnam woke up to in May 2014: The Haiyang Shiyou 981, a US$1 billion (S$1.37 billion) giant Chinese oil rig, parked off its coast, in waters that both countries claim.

Vietnam tried to dislodge the deep-water drilling rig, sending a flotilla of ships its way, but was beaten back by a more forceful response from the Chinese ships that escorted the China National Offshore Oil Corporation rig. The ensuing chaos sparked an international crisis, and a violent nationalistic response within Vietnam.

But it was the silence on one end that quickly moved things onto a different plane — when Vietnam’s communist party leader Nguyen Phu Trong tried to reach Beijing to protest, his calls were not returned. Hanoi wasted no time in turning to the United States, lobbying its former enemy to lift an arms embargo so that Vietnam could buy American lethal weapons to protect itself.

The US partly relaxed the ban, allowing the purchase of non-lethal equipment for maritime defence, and last year, warmly received Mr Trong at the White House.

That visit arguably set in firm motion the full lifting of the arms embargo this week, announced during the first official visit by President Barack Obama to Vietnam.

… “Vietnam is fully in the Russian technological domain, and to break out they will have significant technological problems integrating American weapons into their existing Russian-based armed forces,” said Associate Professor Bernard Loo from the military studies programme of the S. Rajaratnam School of International Studies, adding that he expects more consultations and exchanges between both sides in future.