Russian leader Vladimir Putin visits Vietnam after signing North ...

Russian President Vladimir Putin has arrived in Vietnam for a state visit, a day after signing a mutual defence pact with North Korea's Kim Jong Un, who offered his "full support" on Ukraine.

Mr Putin and Mr Kim inked a strategic treaty at a summit in Pyongyang that included a pledge to come to each other's aid if attacked.

Washington and its allies accuse North Korea of supplying ammunition and missiles to Russia for its war in Ukraine, and the deal fuelled fears of more deliveries.

Sources say that Mr Putin's Vietnam trip will likely include talks in private about defence cooperation.(AFP: Nhac Nguyen)

The US State Department said deepening Russia-North Korea ties were "of great concern" while a top Ukrainian official accused Pyongyang of abetting Moscow's "mass murder of Ukrainians".

Making his first visit to the isolated North in 24 years on Wednesday, Mr Putin said he did not rule out "military-technical cooperation" with Pyongyang, which like Moscow is under heavy international sanctions.

"Today, we are fighting together against the hegemonism and neo-colonial practices of the United States and its satellites," Mr Putin said.

The two countries have been allies since North Korea's founding after World War II and have drawn even closer since Russia's invasion of Ukraine.

The agreement obliges each side to provide "all means at its disposal without delay" if the other is pushed into war. (AP: Korean Central News Agency/Korea News Service)

Reacting to the Pyongyang visit, a US State Department spokesperson said no country should "give Mr Putin a platform to promote his war of aggression against Ukraine".

Mr Putin received a rapturous reception in the North Korean capital, embraced by Kim as he stepped off his plane and greeted by cheering crowds.

His reception is likely to be more reserved in Vietnam, a major global manufacturing hub that has carefully hedged its foreign policy position for years, seeking to be friends with all but beholden to none.

In particular, it has sought to avoid picking sides in the growing US-China rivalry even as both superpowers look to boost their influence in South-East Asia.

Putin will spend Thursday meeting senior Vietnamese leaders including newly installed President To Lam and Nguyen Phu Trong, the powerful general secretary of the ruling Communist Party.

US President Joe Biden visited Hanoi in September to promote ties as his administration seeks to build up Vietnam as an alternative supplier of key high-tech components to reduce American dependence on China.

Vietnam and Russia have a decades-old relationship.(AP: Minh Hoang)

Beijing swiftly followed suit, with President Xi Jinping making his own state visit barely three months later.

Russian officials say Putin's visit will focus on economic, education and energy issues.

But observers say that in private, Ukraine and defence cooperation are likely to be on the table.

Russia and Vietnam have deep ties dating back to the 1950s, and for decades, Moscow was Hanoi's leading arms supplier.

Carl Thayer, emeritus professor of politics at Australia's University of New South Wales, said Vietnam has stopped "big ticket" military purchases since 2022, when Russia invaded Ukraine.

"Russia and Vietnam have a mutual interest in resuming arms sales but Vietnam is hamstrung by the threat of US sanctions," he said.

AFP