On Monday, a day after the reported fall of the Iraqi city of Ramadi to Islamic State forces, the Pentagon downplayed the significance of the loss.

"To read too much into this single fight is simply a mistake," said a Pentagon spokesman."What this means for our strategy, what this means for today, is simply that we, meaning the coalition and our Iraqi partners, now have to go back and retake Ramadi."

The reality is much more complicated. Even as the Islamic State takeover of the capital city of Iraq’s largest province seemed nearly complete on Sunday, the Pentagon continued to argue that the situation was still “fluid and contested.” That assessment was countered by reports that “hundreds of police personnel, soldiers and tribal fighters abandoned the city,” leaving it and a “large store” of American weapons in ISIS hands. The BBC cited a statement “purportedly from IS” claiming that the city had been “purged.”

What the Loss of Ramadi Means for the United States

By Monday morning, Iraqi Shiite militias backed by Iran were seen gathering outside of the city. Prime Minister Haider al-Abadi’s order to mobilize those militias was a risky move for the Iraqi government—Ramadi is a Sunni city in Anbar, a heavily Sunni region; the militias are Shiite.

“We were pushed into a corner,” an Iraqi government official told The Wall Street Journal. “This is not the first choice for many people in Anbar.”

It was also a development that American officials not only didn’t prefer, but evidently didn’t see coming a month ago, when a senior U.S. official told Foreign Policy it was unlikely that Shiite militias would fight the Islamic State in Anbar. The Iraqi government’s growing reliance on Shiite militias to fight ISIS has the potential to undermine American-trained Iraqi security forces. And the fall of Ramadi despite a U.S. air campaign aimed at blunting ISIS’s momentum shows the limits of the American strategy.

What Iran’s Role Means for the United States

Ramadi’s loss, and the mobilization of Shiite militias that has followed, also broadens Iran’s role in the conflict. The Iranian-backed militias include some of the same forces that American troops battled following the 2003 invasion of Iraq. Their growing involvement in Anbar risks exacerbating the country’s dangerous sectarian tensions. The Daily Beast reported that Abadi’s modest efforts to shore up Sunni support in the province were undermined by Nouri al-Maliki, the country’s former prime minister, who enjoys close ties with Iran and the militias now joining the fight in Ramadi.

Meanwhile, the news from the city dovetailed with reports that Iran’s defense minister, Brigadier General Hossein Dehqan, had arrived for talks in Baghdad, just 80 miles east of Ramadi.