North Korean leader Kim Jong-un has inspected Russian nuclear-capable strategic bombers, hypersonic missiles and warships, accompanied by President Vladimir Putin's defence minister.
A smiling Kim was greeted in Russia's Knevichi airfield, about 50km from the Pacific city of Vladivostok, by Defence Minister Sergei Shoigu, who saluted Kim.
The North Korean leader then inspected a guard of honour.
The United States and South Korea fear the revival of Moscow's friendship with Pyongyang could give Kim access to some of Russia's sensitive missile and other technology while helping arm Russia in its war in Ukraine.
Shoigu showed Kim Russia's strategic bombers - the Tu-160, Tu-95 and Tu-22M3 - which are capable of carrying nuclear weapons and form the backbone of Russia's nuclear air attack force, Russia's defence ministry said.
"It can fly from Moscow to Japan and then back again," Shoigu told Kim of one aircraft.
Kim was shown asking about how the missiles were fired from the aircraft, at times nodding and smiling.
Shoigu showed him the MiG-31I supersonic interceptor aircraft equipped with "Kinzhal" hypersonic missiles.
The Kinzhal, or dagger, is an air-launched ballistic missile capable of carrying nuclear or conventional warheads.
It has a reported range of 1500 to 2000km while carrying a payload of 480kg and can travel at up to 10 times the speed of sound (12,000km/h).
Russia's ambassador to North Korea, Alexander Matsegora, told reporters Kim's program was "very intense" and it was not yet clear how long he would remain in Russia, Russian state news agency RIA reported.
After the aircraft and missiles, Kim inspected the warship of Russia's Pacific fleet in Vladivostok, where he was due to watch a demonstration by the Russian navy.
South Korea and the US said on Friday that military co-operation between North Korea and Russia violated United Nations sanctions against Pyongyang and the allies would ensure there was a price to pay.
Russia has gone out of its way to publicise Kim's visit and drop repeated hints about the prospect of military co-operation with North Korea, which was formed in 1948 with the backing of the Soviet Union.
For Putin, who says Moscow is locked in an existential battle with the West over Ukraine, courting Kim allows him to needle Washington and its Asian allies while potentially securing a deep supply of artillery for the Ukraine war.
Washington has accused North Korea of providing arms to Russia, which has the world's biggest store of nuclear warheads, but it is unclear whether any deliveries have been made.
Kim on Friday inspected a Russian fighter jet factory that is under Western sanctions.
He and Putin discussed military matters, the war in Ukraine and deepening co-operation when they met on Wednesday.
Putin told reporters Russia was "not going to violate anything", but would keep developing relations with North Korea.
Kremlin spokesman Dmitry Peskov told reporters there had not been a plan to sign any formal agreements during the visit.
Russian diplomats said Washington had no right to lecture Moscow after the US had bolstered its allies across the world, including with a visit of a US nuclear-armed ballistic missile submarine to South Korea in July.
While in Vladivostok, Kim watched the first act of the ballet Sleeping Beauty, staged by St Petersburg's Mariinsky theatre, the RIA news agency reported.
