I would say that a realistic policy would be that you can not have normal political relations with an Islamic state.
A realistic policy is that Islamic terrorist are not common criminals to be tried in civilian courts.
A realistic policy is that Islamic terrorist are not patriots or freedom fighters and when captured should be summarily executed as illegal combatants.
States that support Islamic terrorism are operating outside the laws of international comity and are committing an act of war. As war like states they shall be attacked by the civilized states and their governments toppled.
This is realistic politics.
Realism in foreign affiars is not just realistic in common sense terms.