Mishustin's two-day visit to Hanoi comes half a year after President Vladimir Putin travelled to the capital, where Vietnam's top leadership indicated a desire to boost defence cooperation with Moscow, its main arms supplier for decades.

The two nations have been close allies since the days of the Cold War.

In a joint statement published Wednesday, Russia said it was "ready to participate in building a national nuclear power industry in Vietnam", and the two nations would work together to implement joint oil and gas projects.

On Tuesday the two sides signed a deal on nuclear energy among seven in a range of fields that also included digital technology and electronics.

Vietnam's Prime Minister Pham Minh Chinh said the country would aim to build a nuclear power plant within five years.

During his visit, Mishustin met all of Vietnam's senior leaders including the Vietnam's general secretary To Lam, the president, prime minister and national assembly chairman.

Russia has been Vietnam's main arms supplier for decades, accounting for more than 80 percent of imports between 1995 and 2023, but orders have dropped off in recent years as international sanctions related to the Ukraine conflict have intensified.

No defence deals were announced during Putin's visit in June, but the two sides said in a joint statement that their defence and security cooperation was "not directed against any third country", and contributed to "peace, stability and sustainable development" in the region.

Putin told reporters during the visit, which came as Western powers stepped up sanctions aimed at constraining Russia's war in Ukraine, that both sides had "identical or very close" positions on key international issues.