Irrationality. Interesting concept.

What would you call someone who simultaneously believes that Russia is nothing but "a gas station masquerading as a country", is fast running out of missiles and ammo, is relying on T-34 tanks from WWII, has poor morale, whose youth are all fleeing the country by the millions - AND YET believes that that SAME country is poised to roll right over NATO and conquer all of Europe?

How could a RATIONAL person keep those two "concepts" in their head?

It means that if you are assigning world-conquering power and ambition to a third-world backwater, you are not being rational, and your fear is thus a type of "phobia".