President Donald Trump has instructed the Pentagon to “annihilate” the Islamic State group in Syria in a bid to prevent escaped foreign fighters from returning home, Defense Secretary Jim Mattis said Friday.

The move to encircle then kill as many jihadists in place as possible — rather than letting them exit a city and targeting them as they flee — reflects an increased urgency to stop battle-hardened jihadists bringing their military expertise and ideology back to European capitals and other areas.

The president has “directed a tactical shift from shoving ISIS out of safe locations in an attrition fight to surrounding the enemy in their strongholds so we can annihilate ISIS,” Mattis said, using an acronym for IS.

“The intent is to prevent the return home of escaped foreign fighters.”