Vietnam is to receive new submarines, aircraft and other military hardware from Russia, under a $2bn agreement signed between the two nations.
Under the contract, Vietnam will purchase six Kilo Class project 636 diesel-electric submarines from Russia, which has undertaken to supply one a year, according to RIA Novosti.
A Russian official said the two sides had also discussed a deal in Moscow for delivery of eight Sukhoi Su-30MK2 jet fighters to Vietnam.
In addition, Vietnam could also purchase a total of 12 Sukhoi fighters worth $600m as well as Svetlyak Class patrol boats and frigates.
The project 636 Kilo Class submarine is one of the world's quietest submarines. It is intended for anti-shipping and anti-submarine operations in relatively shallow waters.
The submarines will be equipped with advanced Club-S integrated missile systems.