According to the FRONTPAGEMAG.COM portal, the tip about the Syrian terrorist who works at a primary school in Berlin came from the US secret service:
“Don’t give Germany too much credit here. The tip seems to have come from the United States.”
If you click on the link, you get the following message:

This is censorship! But here some people get so scared that the background of the Syrian terrorist can be revealed !

frontpagemag.com/point/2019/11/syrian-refugee-who-worked-janitor-german-school-daniel-greenfield/