In this Sept. 6, 2018, file photo, Georgette Mosbacher stands next to an American flag after receiving her credentials as new United States ambassador to Poland in Warsaw. Credit: Czarek Sokolowski | AP

The row started when Russia’s president, Vladimir Putin, was asked about the Nazi-Soviet Pact of 1939 during his annual press conference on Dec. 19, and gave a deliberately evasive answer.

Or maybe it started in September, when the European Union’s parliament passed a resolution describing the Second World War as “an immediate result” of the Nazi-Soviet deal. That was done to placate the Polish government, which wants to remind everybody that both the Germans and the Russians invaded Poland in 1939.

However, that infuriated the Russians, whose 20th-century history holds little that they can be proud of apart from their victory over Nazi Germany in 1941-45, after Hitler broke the pact and invaded the Soviet Union. Yet here was the European Parliament effectively saying that it was their stupid fault for making an alliance with Hitler.

Russian propaganda output since then has tried very hard to blur what actually happened in 1939 — and then just before New Year’s Georgette Mosbacher, the U.S. ambassador to Poland, entered the fray, sending out a tweet that said: “Dear President Putin, Hitler and Stalin colluded to start WWII.” Even the Poles haven’t been that crude: she might as well have poked Putin with a stick.

Anyway, she said it. Was she right? I used to be a professional historian until I discovered that journalists have more fun and make more money, so here’s my best estimate.

Nobody actually “wanted” the Second World War: it was only 20 years since the First World War ended, and memories were too fresh. But Hitler wanted certain territories, he was willing to fight some small wars to get them and he was a gambler, big on bluff. He probably did intend to attack the Soviet Union, too, in the end — but only later.

Putin makes much of the British and French decision to give Germany the German-populated border regions of Czechoslovakia in the Munich agreement of 1938. This allegedly showed Stalin that they would only appease Hitler, not fight him. And that, Putin has said, is why Stalin made a deal with Hitler.

This is nonsense: the dates don’t work. The Munich agreement was one last try by Britain and France to satisfy Hitler’s more-or-less reasonable demands by letting him have German-majority territories that had been given to other countries at the end of the First World War. But the British did not believe that Hitler was actually reasonable.

Britain, under Prime Minister Neville Chamberlain, had actually started high-speed rearmament in early 1938: British weapons production doubled in 1938, and again in 1939. And when Hitler started talking about seizing part of Poland in 1939, Britain and France both said specifically that they would go to war to stop him.

Stalin knew perfectly well that Britain and France were ready to fight Hitler in 1939: there were actually British and French diplomats in Moscow trying to negotiate an anti-Nazi alliance that August. He simply got a better offer from Hitler: Germany would invade Poland, but give Stalin the eastern half — and throw in Latvia, Lithuania and Estonia for free.

So the Nazi-Soviet Pact was signed in Moscow on Aug. 23, 1939, and Hitler invaded Poland on Sept. 1.

Britain and France declared war on Germany, as they had promised, but they couldn’t save Poland. The Soviet Union invaded Estonia, Latvia and Lithuania at once, but waited two weeks, until the Germans had destroyed the Polish army, before occupying its half of Poland. And all those territories remained part of the Soviet Union until it finally collapsed 50 years later, in 1989.

That’s what actually happened. Stalin was a complete idiot to trust Hitler, but went on supplying Germany with oil and various other scarce goods until the day before Germany invaded Russia in June 1941. It’s not a story that reflects well on Russia, so it’s no wonder that Putin keeps trying to change the narrative.

You can see why the Poles want to keep the story straight, too. But Putin is not Stalin, and Stalin was not planning to conquer the world, just trying to recover territories that Russia had lost at the end of the First World War. In fact, nobody was planning to “conquer the world” or even to start a second world war. They just miscalculated, as usual.

Gwynne Dyer’s new book is “Growing Pains: The Future of Democracy (and Work).”