Locally, Putin's aim is to recover for Moscow the clout on the peninsula that Gorbachev lost by hastily recognizing South Korea in 1990. Ironically, part payment was made in military materiel, including tanks more modern than any ever supplied to North Korea. Submarines are on offer too, but the South Korean navy is not keen. Of the four powers involved in Korea by geography or history, the US and China are party to four-way talks with the two Koreas, while Japan is a board member of the KEDO consortium. That long and hardly happy history suggests other potential pitfalls for this new comradeship.
Money is one.
If at one level a political act, this is also a commercial transaction - or so Moscow intends. But Pyongyang's notorious reluctance to pay for anything didn't just begin with the Western banks that it took to the cleaners in the 1970s. Both long before and after that, it didn't pay Moscow either. The cumulative debt has now been fixed at 3.7 billion old roubles, but they are still arguing over a conversion rate. So North Korea may not get the goodies unless it pays for them.