Islamic State group militants cornered in their last foothold in eastern Syria fought back with suicide car bombs, snipers and booby traps Monday, slowing Kurdish fighters advancing under the cover of U.S.-led coalition airstrikes, Kurdish news agencies and a Syrian war monitor said.

Their home countries don’t want them and holding trials in Syria isn’t an option: now suspected foreign terrorists could end up facing tough justice over the border in Iraq.

The U.S.-backed Syrian Democratic Forces (SDF) began an assault against the final Islamic State enclave in eastern Syria on Saturday, aiming to wipe out the last vestige of the jihadist group’s “caliphate” in the SDF’s area of operations.