Well I haven't noticed any Buddhist terror attacks taking place in Western countries, by Western born Buddhists, or by Buddhists at least growing up in the West. (Or even recent migrants.)
I'm pretty sure that kind of terror threat would be tiny compared to the threat in the Western world of Islamic terrorism. Now there are a lot less Buddhists living in the Western world, but still, they don't appear, on the face of it, to have the same tendency towards terrorism.
If you can show examples of Buddhist terrorism taking place in the West that I have missed? And these need to be *religiously* motivated of course: "We carry out these attacks in the name of Buddha" or something along those lines. It can't just be a Buddhist that had a political cause, but never claimed their religious worldview was also central to their actions. There would also need to be multiple cases for there to be any chance of a real comparison to Islamic terrorism.
Obviously you can find examples of Buddhists being violent, in some sort of way, some of the time, in various places and times, as you could for most or virtually all groups.