Russian President Vladimir Putin has praised North Korea for “firmly supporting” Moscow’s war in Ukraine, ahead of his first visit to Pyongyang in 24 years.Mr Putin is expected to arrive in the capital to meet North Korean leader Kim Jong Un on Tuesday.The two leaders last met in September at the Vostochny cosmodrome in Russia’s far east, but this is Mr Putin’s first visit to Pyongyang since 2000.In a letter published in North Korean state media, Mr Putin promised to build trade and security systems with Pyongyang “that are not controlled by the West”.President Putin also vowed support for Pyongyang’s efforts to defend its interests despite what he called “US pressure, blackmail and military threats”, in the article printed in Rodong Sinmun, North Korea’s ruling party mouthpiece.He said the two countries would continue to “resolutely oppose” what he described as Western ambitions “to hinder the establishment of a multipolarised world order based on mutual respect for justice”.The United States said it was concerned about the “deepening relationship between these two countries”. The Kremlin has described the event as a “friendly state visit” with Russian media reporting Mr Putin and Mr Kim may sign a partnership agreement, including on security issues, and will give joint statements to the media.A parade in Kim Il Sung square is anticipated. Mr Putin is also expected to watch a concert and visit the Orthodox Church of the Life-Giving Trinity in Pyongyang, the only orthodox church in North Korea.There are reports Mr Putin will stay at the Kumsusan guesthouse in Pyongyang, where Chinese leader Xi Jinping last stayed during his state visit to North Korea in 2019.Mr Putin is expected to arrive with his new defence minister, Andrei Belousov, while Foreign Minister Sergei Lavrov and Deputy Prime Minister Alexander Novak will also be part of the delegation.Mr Kim said last week that ties with Russia had “developed into an unbreakable relationship of comrades-in-arms”.During their meeting last year, Mr Putin said he saw “possibilities” for military cooperation with North Korea, while Mr Kim wished Russia’s president “victory” in Ukraine.The White House said the US is concerned about closer ties between Russia and North Korea.”We’re not concerned about the trip” by Mr Putin, National Security Council spokesman John Kirby told reporters on Monday. “What we are concerned about is the deepening relationship between these two countries.”John Nilsson-Wright, head of the Japan and Koreas programme at Cambridge University’s Centre for Geopolitics, said Mr Putin is “strengthening ties with its old Cold War partner” in an effort to “counter any suggestion that the US and its allies have been able to isolate Moscow”.”He is bolstering relations between authoritarian regimes at a time when democratic governments are in a defensive position, confronting global security challenges” in the Middle East, East Asia and Ukraine, he added.In 2000, at the start of his presidential career, Mr Putin met Mr Kim’s father, Kim Jong Il, who was still supreme leader. Ties between the two pariah states have increased in recent years, especially since Russia’s full-scale invasion of Ukraine.North Korea needs help with space technology after its recent failure to put a second spy satellite into orbit – as well as food, fuel, and foreign currency. While Russia faces a continued shortage of weapons in its war in Ukraine.Washington and Seoul have accused Pyongyang of supplying Moscow with artillery and other equipment, most likely in exchange for food and military aid and technology. Both North Korea and Russia deny the existence of an arms deal.After North Korea, Mr Putin is expected to visit Vietnam, a Communist state and long-time ally, where both countries are expected to discuss issues such as trade.