Islamic State came closer to gaining full control of Iraq’s Anbar province after it seized a military base to the west of Baghdad that had been one of the government’s few remaining outposts there.

Militants seized the base, located near the town of Hit and a major highway from Baghdad to the Syrian border, after heavy fighting with soldiers, according to Ahmed al-Dulaimi, a Sunni tribal leader. Its capture increases the threat to Ramadi, Anbar’s capital, and to Iraq’s second-largest dam at Haditha.

The insurgent group has declared a caliphate that stretches across much of northern Syria and Iraq, prompting the U.S. to launch a bombing campaign backed by European and Arab allies to halt the advance. The group’s recent gains to the west of Baghdad have sparked concern it’s preparing to attack the capital. […]