Russia and Vietnam concluded several deals during a one-day visit by Russian President Vladimir Putin to the Southeast Asian country.
Putin, who met with Vietnamese President Truong Tan Sang, said Vietnam agreed to buy more military hardware from Russia. Hanoi is due to receive five more diesel submarines from Russia by 2016.
Putin said talks were also held on creating a free-trade zone between the Russian-led Customs Union and Hanoi.
Russian firms Rosneft and Gazprom signed several deals with state energy company Petrovietnam.
Separately, Russia agreed to loan Vietnam $8 billion to build its first nuclear power plant. Communist Vietnam is one of Russia's closest Asian allies -- some 90 Russian firms are operating in the country.
Putin was due to travel next to South Korea.
Based on reporting by dpa and Reuters