There is even a silver lining in the fall of Ramadi. Before last week, many Iraqi leaders seemed to have forgotten that the Islamic State was still a threat and failed to give credit to those doing the most to resist it. The former prime minister Nuri Kamal al-Maliki — whose own inept security policies helped create the Islamic State — railed against Iraqi Kurdish aspirations for independence, despite the Kurds’ valiant efforts to neutralize the Islamic State in northern Iraq. The governor of Nineveh Province, Atheel al-Nujaifi, was in Washington early this month advocating an autonomous Sunni region even while his capital, Mosul, was in the Islamic State’s clutches. During my trip to Iraq in March, other elites spoke to me as though the Islamic State had already been destroyed. Ramadi has ended their complacency.

But the fall of Ramadi, the capital of Anbar Province, does not mean that Anbar is lost. The Iraqi government still controls vital military infrastructure there, including two air bases, which must be defended.

Anbar was the birthplace of the Sunni awakening movement during the American presence in Iraq. Prime Minister Haider al-Abadi, a Shiite, initiated an effort in early April to arm the Iraqi Sunni tribes in Anbar so that they could fight the Islamic State. He can now make a strong case that arming the tribes is a crucial priority; seizing this opportunity would also help him regain political strength. In the long term, an effective tribal force in Anbar could allow Mr. Abadi to rely less on the Shiite armed groups.