They discussed sending a North Korean cosmonaut into space aboard a Russian rocket, according to state media in Moscow.
Kim, who runs the world’s most secretive regime in North Korea with brutal repression, heaped praise on Putin, whose invasion has killed tens of thousands of Russian and Ukrainian soldiers, as well as thousands of civilians.
But Prime Minister Rishi Sunak’s spokesman said: “This visit serves to highlight Russia’s isolation on the global stage. And as the world unites against Putin’s illegal invasion of Ukraine, he has been forced to turn to regimes such as North Korea for help.”
The spokesman said that Russia’s “negotiation of deals with significant quantities of weapons from the DPRK (North Korea) to be used against Ukraine violates UN Security Council resolutions, including resolutions, Russia itself voted for”.
“We urge DPRK to cease its arms negotiations with Russia and to abide by public commitments Pyongyang has made not to sell arms to Russia.”
US and South Korean officials have expressed concern that Kim will provide weapons and ammunition to Russia, which has expended vast stocks in more than 18 months of war in Ukraine.
In return, North Korea would get help for its ailing programme to put up spy satellites.
But Alicia Kearns, chair of the Commons foreign affairs committee at Westminster, told The Standard: “The Putin-Kim meeting confirms Russia’s isolation, and his willingness to define his own legacy as one dependent on tin pot dictators accused of mass torture and executions.
“The concern primarily is arms sales which Putin would use to continue war crimes in Ukraine...Putin it seems will embrace anyone to continue his murderous path. In return it seems Putin may help Kim continue his vanity projects conducted at the cost of the lives of North Koreans, including space and satellite partnerships.”
The Russian president’s increasing isolation, after he launched his bloody war in Ukraine in February last year, was further evident from his failure to turn up to the G20 summit in Delhi, and the lower number of African leaders who attended a summit in St Petersburg than had gone to a similar Russia-Africa gathering in 2019.
Putin and Kim began their meeting with a tour at Russia’s remote Vostochny Cosmodrome, a satellite launch facility, on Wednesday, suggesting North Korea could be seeking Russian help to develop military satellite technology.
The talks came hours after North Korea fired two ballistic missiles toward the sea in its latest provocation towards South Korea. South Korean officials didn't immediately say how far the North Korean missiles flew.
Asked whether Russia will help North Korea build satellites, Putin was quoted by Russian state media as saying: “That’s why we have come here. The DPRK [North Korean] leader shows keen interest in rocket technology. They’re trying to develop space, too.”
Asked about military cooperation, Putin added: “We will talk about all issues without a rush. There is time.”
Putin welcomed Kim’s limousine, brought from Pyongyang in the North Korean leader’s special armoured train, at the entrance to the launch facility with a handshake that lasted around 40 seconds.
The Russian leader said he was “very glad to see” the North Korean dictator, while Mr Kim’s translator thanked Putin for the warm welcome, “despite being busy."
Kim claimed Putin’s regime was fighting a “sacred” war with the West and that the two countries would together battle with “imperialism”.
North Korea may have tens of millions of ageing artillery shells and rockets based on Soviet designs that could give a huge boost to the Russian army in Ukraine, analysts say.
The North Korean delegation included Jo Chun Ryong, a ruling party official in charge of munitions policies.
Mr Kim said his decision to visit Russia four years after his previous visit showed how Pyongyang is “prioritising the strategic importance" of its relations with Moscow, North Korean state media said.
Alongside military technology, he could also seek economic aid for his regime. An arms deal would violate international sanctions that Russia supported in the past.
The US has previously accused North Korea of providing Russia with arms, including selling artillery shells to the Russian mercenary group Wagner, which it denies.
Speculation about their military cooperation grew after the Russian defence minister visited North Korea in July, touring a weapons factory.