Seems evident at least that strategy is failing. Why not accept that they exist and open a dialogue? Best case, they're ambitious sociopaths using violence as an aesthetic. Worst case they're zealots. At any rate, they've clearly bought equity in the geopolitical conversation. If they cannot be bought out, we will need to weigh our need for safety against our values. Because eradicating them will mean murdering many, many, many non-combatants.