That’s been their MO for years now, they are so used to invading countries with no more organized resistance than some guerilla fighters (who usually end up beating them back anyway), they can’t help but underestimate The Bad Guys as being technologically inferior to them. The idea of fighting someone that has most of, if not all of, the same capabilities as you is absolutely foreign to them.

Even after over a year of evidence being provided to the contrary, they simply cannot believe it.