ERBIL, Iraq — The Islamic State (IS) has in recent days claimed responsibility for a rocket attack on the Siniya oil refinery in Iraq’s northern Salahuddin province and for the killing of soldiers, policemen, local officials and others in neighboring Anbar.

In Shirqat, also in northern Salahuddin province, the bodies of two villagers were found beheaded on Nov. 28. The attacks in Anbar occurred a few days after a border crossing with Saudi Arabia reopened following a 30-year closure.

Though far from holding any major territory, the transnational group — which Iraq announced the defeat of within its borders three years ago — continues to operate in areas that insurgents have used as hideouts for decades, such as the Hamrin Mountains and desert areas.

Some major figures seem to be able to elude capture for significant periods. Recent arrests in Iraq’s largest cities have included that of IS’s “administrative chief" — a man known as Abu Naba — who had reportedly been responsible for getting funding for the group and relaying messages between members. Naba was arrested at the Baghdad airport in October. Also, a woman was arrested Nov. 27 in Mosul; she had reportedly been working with IS when it was in control of the city. Victory against IS in Mosul was declared in July 2017 and in Iraq in December 2017.