Europe is currently so hostile to receiving the people who need to move there that they might be surprised how much hostility they're met with if/when the tables turn.
Europe has the technology and experience to solve geo-social problems by turning itself into a cozy castle with high walls. The hostiles will be used as feedstock for alcalic hydrolysis at industrial scale/faster than replacement/birthing rate until the zones have been fully sanitized. Problems turned into fertilizer for nukkular powered greenhouses.