Seoul and Washington have expressed concern that Russia could be trying to acquire ammunition from North Korea to supplement its thinning stockpiles amid its war in Ukraine.

The trip and summit with Russian President Vladimir Putin received global attention since the leader seldom leaves his country and drew concerns over possible arms trade and technology transfer with Russia.

The Kremlin says Russia and North Korea have not signed any agreements on military matters or on any other areas during Kim's visit.

The plant produces Russia's most modern fighter jets.

For the US and allies, the burgeoning friendship between Kim and Putin is a concern.

He also orders further reinforcing the country's war deterrence with 'increasing speed'.

South Korea and the US have warned since early 2022 that North Korea may resume nuclear testing at any time.

He says the country should be fully ready to use the weapons at any time.

It is designed to unleash a 'radioactive tsunami' that would destroy enemy naval vessels and ports, state media says.

This could hint at another year of intensive weapons tests and tension.

The days-long gathering of party and government officials caps a year when the isolated country fired an unprecedented number of missiles, including intercontinental ballistic missiles.

North Korean scientists have made a 'wonderful leap forward in the development of the technology of mounting nuclear warheads on ballistic missiles,' Kim Jong Un says.