Do find a lot of examples of neo-Nazi idiots with hundreds of millions of stolen dollars and heavy weapons rounding up thousands of people and promising to slaughter them because of their religion, or marching cops and soldiers into trenches and machine gunning them down?
The "rounding up people" part might not be happening right now, but if you google phrases like "neo-nazi weapons stockpile" and "neo-nazis murder cop," you'll find plenty of examples. Don't the people of Europe have a right to use a pre-emptive strike to defend themselves against the inevitable escalation of violence from these barbaric individuals from reaching their shores*?
*In case it's not glaringly obvious, yes, I'm mocking the "fight them there so we don't fight them here" warhawks.
Neo-Nazis talk a lot. But they're just noisy idiots.
Neo-nazis kill people - Anders Breivik ring a bell?. That's not being "just noisy idiots." No, today they aren't killing people in the volumes that ISIL is, but that's today. Tomorrow could be completely different.
Actually, Breivik shows the point I'm making quite well: many would claim his style of extremism is an exclusively American export. If American neo-nazis can influence him, they can influence thousands of others, and by the "fight them there not here" mentality, that means other nations "have a duty" to bomb American neo-nazis into oblivion, sovereign borders be damned.
I'm really not sure why you mischaracterize neo-nazis as a non-violent group; ignorance is hard to believe... confluent opinions, perhaps?