According to Irlmaier, what kicks off the sudden Russian invasion is when some "Great One" gets αssαssιnαtҽd in the Balkans. Given that Russia reacts, and starts by wiping out Prague (the Golden City), I would venture to say it was a Russian diplomat (Putin himself?) murdered by someone from the Czech Republic (some diplomat?).
People don't know that there are many much HARDER-liners in the Russian Duma than Putin. Putin is seen as a moderate. Just yesterday, some members of the Duma were demanding reparations from the US over the sanctions, including returning Alaska to Russia and said that Russia should nuke the US if we don't comply. So if Putin were taken out, I could see some of the right-wing radical types just blasting into Western Europe without warning.