18% of Muslim "violent extremists" in the US cited anger at US military interventions in Muslim countries as a reason. It was the most common single reason cited.

I expect the number of jihadis motivated by this in other countries is in the thousands or tens of thousands.

Some of these interventions initially had a justification, but it has evaporated. Some of them never had any justification. Either way, we need to stop these wars, for our self interest as well as in the name of justice.