"Hamas is itself an Islamist resistance movement, with a resistance "army" called al-Qassam, but Hamas members are seen as infidels by ISIS since they place the nationalist battle for a Palestinian state before the campaign for a caliphate. Hamas's willingness to negotiate with Israel and to agree to a cease-fire last summer was seen by ISIS as the latest demonstration of its collaboration. ISIS supporters inside Gaza have shown their opposition and tried to break the cease-fire by firing rockets into Israel, thereby angering Hamas and risking heavy Israeli retaliation."