The move comes amid hope of large-scale investment from Seoul into Siberia.
Going by train all the way from Beijing (or even London) to New York could become a reality.
Fears for plan to stimulate Russian economy via major infrastructure links to Asia and Europe as Beijing announces rival scheme.
Officials from Russia and North Korea say the long-waited train connection is now almost ready.
The distance between capital city Moscow and key Siberian cities could shrink in plan envisaged by the Kremlin leader.
The Russian government is to give priority to Siberia and the Far East as it puts modernisation on fast-forward, insists Dmitry Medvedev.
Possible route could see 400km/hour bullet train pass through heart of Siberia and Altai region with stops in major cities.
One estimate is half a million new jobs stemming from improvements to the Baikal-Amur Mainline link amid hopes of foreign investment.
33 hour journey between the capitals could be in place by 2020.