[Mariner]

"Russia is to blame for both world wars"

That's a leap right there.

What did Russia have to do with France and Britain declaring war against Germany and Austria?

To support Russia, against whom they both warred?

[Tailgunner Joe]

At the beginning of the Great War, France and Britain were allied with Russia. - Triple Entente

That is why the Schlieffen Plan called for Germany attacking and defeating France quickly before turning around to fight Russia.