The Islamic State group on Friday took control of the provincial government center of Ramadi, the capital of Iraq’s largest province, and appeared to be in control of most of the city in a major defeat for the Iraqi government.

Islamic State forces also appeared to be closing in on government positions in two other key locations in Anbar province, the towns of Baghdadi and Karmah, in a broad offensive that if successful would end the government presence in all of the province’s major population centers. The capture of Baghdadi also would cut the supply lines to the Iraqi garrison protecting the strategic Haditha Dam.

U.S. officials offered conflicting views of the events, with the State Department and the Pentagon at first downplaying the significance of what had taken place. But a later statement from the White House made it clear that the situation was urgent and that the United States was rushing shipments of heavy weapons, ammunition and supplies to Iraq to deal with the Islamic State advance. […]