When I was going through the archives of my local web analytics company, I found another interesting case, when major government in Europe was cheated and lost its national treasure to Bolsheviks. This case is related to the Civil war in Spain in the thirties of the twentieth century. It is called infamously Moscow gold case.
Short lived Spanish Republic desperately needed arms and military equipment but other European countries did not want to get involved in the civil war and did not sell anything to the Spaniards. The only country that ignored this embargo was the Soviet Union. That is why in 1937 the Spanish republic sent most of the gold reserves from its national Treasure to Russians. One must say, that at the time Spain was on the fourth place in the world for its stored gold. And the USSR got most of it, which amounted at the time to five hundred million dollars.
When Franco and his supporters learned about it, they heavily protested this transaction, stating that this gold belongs to the people and not to the Spanish government. But the transaction turned sour for the republicans because Soviets sold them all kind of military junk stored since World War I. Besides, prices were extremely inflated for each rifle and each bullet. This outdated equipment, part of which was malfunctioning right from the start, turned out to be one of the huge factors that impacted the defeat of the Spanish Republic.