SEOUL - Russian President Vladimir Putin was in South Korea on Wednesday to push a pet project for a new major trading route linking Asia and Europe by rail that requires prying open North Korea.Mr Putin hopes his brief visit will include the signing of a memorandum of understanding on the ambitious project, which envisages an "Iron Silk Road" uniting the rail networks of South and North Korea and connecting them to Europe via the Trans-Siberian Railway.Russia took a first step in September, when it completed a 54-kilometre track from the its south-east border town of Khasan to the North Korean port of Rajin.Located in the far north-east, where the borders of North Korea, Russia and China converge, Rajin offers a warm-water port for the North's two giant neighbours.Mr Putin's desire is to see the rail link extended through North Korea, across the world's last Cold War frontier, and all the way down to the southern South Korean port of Busan.Media reports say Russia is looking for South Korea to take a 34 per cent share in the project, with Moscow holding 36 per cent and Pyongyang 30 per cent.POSCO, Korail, and Hyundai Maritime have been suggested as possible members of a consortium to take on the South Korean share.Dr Andrei Lankov, a Russian expert on North Korea who teaches at Seoul's Kookmin University, remains "very sceptical" about the entire project given the volatility of inter-Korean relations and the international community's struggle to contain the North's nuclear ambitions."The idea itself makes perfect sense from a trade and economic viewpoint," he told AFP."But this is clearly going to cost billions of dollars and what companies are going to risk that much investment with North Korea in the current climate?" he asked."I'm sure North Korea will be keen, because once it got started, it would provide Pyongyang with a new project to manipulate and use to pressure others," he added.Dr Lankov said the same financial and political risks applied to plans to build a pipeline to supply both Koreas with Russian natural gas.Observers highlight the precedent of the Kaesong industrial zone jointly run by North and South Korea, which Pyongyang unilaterally shut down in April as military tensions surged.The zone reopened in September, but South Korean factory owners said they lost a small fortune during the five-month closure.Mr Putin is expected to bring up both the rail and the gas projects with South Korean President Park Geun Hye, whom he last held talks with on the sidelines of a G20 meeting in Saint Petersburg in September.The two leaders will also discuss North Korea's nuclear weapons programme, amid signs that Pyongyang, despite UN sanctions, is moving ahead on all fronts to acquire a credible nuclear deterrent.Russia is a member of the stalled six-party talks on North Korea's nuclear programme, along with China, the United States, Japan and the two Koreas.China and North Korea have been pushing for a resumption of the dialogue, but Seoul and Washington insist Pyongyang must first show some genuine commitment to denuclearisation.