manpower

Experts have questioned the success of the offensive, with one calling it a "strategic catastrophe" given manpower shortages faced by Ukraine.

Russia's biggest advantage is manpower and it has shown a willingness to throw soldiers at Ukrainian positions to gain a few metres at a time.

Observers say Moscow needs manpower, while Pyongyang needs money and technology.

Even if not numerically significant, any infusion of manpower can count at a time when both sides are suffering attrition and scrambling to find recruits.

Ukraine's military has been under severe pressure of late, in part due to Russia's greater manpower and deeper resources.