Hundreds of Iraqi soldiers were trapped or missing Sunday after a chaotic retreat from an army base in western Iraq, military officials said, underscoring the ability of Islamic State insurgents to remain on the offensive despite expanded airstrikes by the United States.

At least 820 soldiers were stationed at Camp Saqlawiyah in Anbar province, north of the insurgent-controlled Iraqi city of Fallujah, when it came under attack from five suicide bombings Sunday afternoon, said Lt. Col. Ihab Hashem, a deputy commander with the Iraqi army’s 8th division who was at the camp. Two bombers drove explosives-packed armored vehicles and three others detonated vests, he said.

In a statement Sunday night, Iraq’s Defense Ministry confirmed that it had lost contact with some of its “heroic soldiers” during operations in Anbar but did not give numbers. It vowed to continue to “clean every inch of land” of militants. […]