The Japanese are. It's any racial group that Jews think would and could unite to destroy them.
I think Muslims aren't a worry because they always rip themselves apart with factionalism. European factions align along ethnic lines but co-exist with the others, uniting against external threats. Muslims, historically, play a zero sum game where the winner forms an empire and the loser is oppressed until they can seize power. Jews insinuate themselves into Empires like water climbing a paper towel.
I think Muslims aren't a worry because they always rip themselves apart with factionalism. European factions align along ethnic lines but co-exist with the others, uniting against external threats. Muslims, historically, play a zero sum game where the winner forms an empire and the loser is oppressed until they can seize power. Jews insinuate themselves into Empires like water climbing a paper towel.