How much impact would North Korean weapons have on the Ukraine battlefield?

With North Korean leader Kim Jong Un expected to meet his Russian counterpart Vladimir Putin soon, all eyes are on a potential weapons deal between the two nations.

The US warned last week that Russia and North Korea are "actively advancing" their arms negotiations, adding that Pyongyang would "pay a price" if it struck a deal with Russia and provided weapons to be used against Ukraine.

But Joseph Dempsey, research associate for defense and military analysis at the International Institute for Strategic Studies, said North Korean ammunition is unlikely to change the direction of the war -- only prolonging it and replenishing Russia's depleted supplies.

Others questioned how quickly any North Korean ammo could get into the hands of Russian troops on the frontlines in Ukraine.

Shipments from North Korea to Russian fighting forces would need to cross the Trans-Siberian Railway, more than 5,700 miles from Vladivostok in the east to Moscow in the west.

Much of the equipment on the rail line is from the late Cold War era, and seriously stressed, said Trent Telenko, a former quality control auditor for the US’ Defense Contract Management Agency who has studied Russian logistics.

“Overstressing Cold War-era transportation is a seriously stupid idea on a lot of levels. And that is exactly what the Russians are doing,” Telenko said