This 25 March 2019 video from the USA says about itself:
‘This could happen anywhere’: Police investigate possible arson at California mosque
Translated from Dutch NOS TV today:
A man from Leeuwarden has been sentenced to 36 months in prison, of which 14 months suspended sentence, for arson at a mosque in his place of residence. He also has to pay compensation of around 1300 euros.
… He [the perpetrator] says he thought it was an empty building, but the court does not agree. The man lived close to the mosque and according to the judges he must have seen that several hundred people came to the mosque every week. …
The court says that the man with his action has caused great danger to the mosque and to the imam. In addition, the judges blame the man for causing fear in the local religious community. During the court case, representatives of the mosque said that since the arson, far fewer people come to the mosque, despite the extra security measures that have been taken.