I don't think this phrase is defensible, because "significant" in that context is very subjective. Nevertheless, the German intelligence estimates there are 2000 extremists that could cause trouble. This is something completely separate from criminals like ordinary robbers or rapists - people with an ideology could be more dangerous, and, unfortunately, every few years they hit headlines in Europe. Everybody is aware of this so nobody is surprised if armed guards ask you if they can look into your bag for example, or there are massive blocks preventing attacks with trucks. So no wonder people long for the old times when they had to deal mainly with local bandits.

[0] https://www.welt.de/politik/deutschland/article233732426/Ver...