Rashid considers the steps of Ukraine to be a primary invasion route from Europe. I'm talking about the same Europe that has invaded Russia multiple times in the past 200 years. They want strategic depth with NATO and the Ukraine becoming part of NATO would leave western Russia open to invasion along the flat Ukrainian steppe and vulnerable to first missile strikes.
If the US lost 30 million, like the Russians did in WWII, due to an invasion from Mexico, we would feel the same way, too. We proved that in 1962.