And to further your point mass immigration into Europe isn't just recent; it's been happening for decades. For a while the Islamic state was encouraging attacks in Europe, and hundreds of people were killed by jihadists running cars through Christmas parades and similar events which peaked ~2016 and 2017. I think the largest was an attack in Nice, France on Bastille day killing 86 and injuring hundreds (https://grokipedia.com/page/2016_Nice_truck_attack) and another famous one I can think of was the christmas market attack in Berlin, killing 12 and injuring 56 (https://grokipedia.com/page/2016_Berlin_truck_attack). These were the result of economic immigration, unrelated to anything specific the US had done.