Stewart Baker offers this suggestion:
Europeans should be conscripting military-age Syrian refugees, training them, and sending them back to fight for their own country. (According to the United Nations, in this wave of migrants, the men outnumber the women by nearly five to one.) Why shouldn’t those men be asked to help create the refuge that they and their families need — in Syria, where they need it most.
I can’t imagine anything more likely to be effective. Read the whole thing.