WASHINGTON >> The Islamic State group’s takeover of the provincial capital Ramadi is stark evidence that Iraqi forces lack the “will to fight,” Defense Secretary Ash Carter acknowledged, a harsh assessment that raised new questions about the Obama administration’s strategy to defeat the extremist group that has seized a strategically important swath of the Middle East.

Although Iraqi soldiers “vastly outnumbered” their opposition in the capital of Anbar province, they quickly withdrew last Sunday without putting up much resistance from the city in Iraq’s Sunni heartland, Carter said on CNN’s “State of the Union.” The interview aired on Sunday.

The Iraqis left behind large numbers of U.S.-supplied vehicles, including several tanks, now presumed to be in Islamic State hands.

“What apparently happened is the Iraqi forces just showed no will to fight,” Carter said. “They were not outnumbered; in fact, they vastly outnumbered the opposing force. That says to me, and I think to most of us, that we have an issue with the will of the Iraqis to fight ISIL and defend themselves.”

The White House declined to comment on Sunday.

Iraqi lawmaker Hakim al-Zamili, the head of the parliamentary defense and security committee, called Carter’s comments “unrealistic and baseless,” in an interview with The Associated Press.

“The Iraqi army and police did have the will to fight IS group in Ramadi, but these forces lack good equipment, weapons and aerial support,” he said. “The U.S. officials should provide Iraq with advanced weapons as soon as possible instead of making such statements.”

American officials say they are sending anti-tank weapons to the Iraqi military. But they also noted that Iraqi forces were not routed from Ramadi— they left of their own accord, frightened in part by a powerful wave of Islamic State group suicide truck bombs.

“The ISF was not driven out of Ramadi,” Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, said last week. “They drove out of Ramadi.”

The fall of Ramadi has sparked renewed questions about the effectiveness of the Obama administration’s approach in Iraq, a blend of retraining and rebuilding the Iraqi army, prodding Baghdad to reconcile with the nation’s Sunnis and bombing Islamic State group targets from the air without committing American ground combat troops.

Obama’s approach is predicated on the Shiite-dominated government in Baghdad granting political concessions to the country’s alienated Sunnis, who are a source of personnel and money for the Islamic State group. But there has been little visible progress on that front. Baghdad has continued to work closely with Shiite-dominated militias backed by Iran, which have been accused of atrocities against Sunnis, a religious minority that once ruled Iraq.

The U.S. has sought to reach out on its own to Sunni tribes and is training some Sunni fighters, but those efforts have been limited by the small number of American troops on the ground.

Carter defended the use of U.S. airstrikes as an effective part of the fight against the Islamic State group, but he said they are not a replacement for Iraqi ground forces willing to defend their country.

“We can participate in the defeat of ISIL,” he said. “But we can’t make Iraq … a decent place for people to live — we can’t sustain the victory, only the Iraqis can do that and, in particular in this case, the Sunni tribes to the West.”

American intelligence officials have assessed for some time that Iraq is unlikely ever again to function as the multi-ethnic nation-state it once was, and that any future political arrangement would have to grant significant local autonomy to the three main groups_Sunnis, Shiites and Kurds. But the Obama administration has continued to pursue a “one Iraq” policy, routing all assistance through Baghdad.

Over the past year defeated Iraq security forces have repeatedly left U.S.-supplied military equipment on the battlefield, which the U.S. has targeted in subsequent airstrikes against Islamic State forces. The Pentagon this past week estimated that when Iraqi troops abandoned Ramadi, they left behind a half-dozen tanks, a similar number of artillery pieces, a larger number of armored personnel carriers and about 100 wheeled vehicles like Humvees.

Carter did not discuss any new U.S. tactics in the fight against Islamic State group.

U.S. lawmakers from both parties criticized the administration’s strategy Sunday, urging a more aggressive posture.

Rep. Tulsi Gabbard, D-Hawaii, an Iraq war veteran, cast doubt on the U.S. preference to deal only with the Shiite-dominated government in Baghdad, calling instead for directly arming both the Kurds in the north and Sunni tribes that have asked for help in beating back the Islamic State group.

“These Iraqi security forces have cut and run,” Gabbard said. “They cut and ran and dropped their weapons when they were faced with their first real battle with ISIS.”

She criticized Baghdad’s close links with Iran-backed Shiite militias that have declared themselves enemies of the United States.

Republican Sen. John McCain, who chairs the Armed Services Committee, called for thousands of U.S. troops on the ground in Iraq, including spotters who can better direct air strikes.

“We need to have a strategy,” he said. “There is no strategy. And anybody who says there is, I’d like to hear what it is.”

Even Obama administration allies were urging the president to do more.

“I think there is a major hesitation to get too deeply involved in Iraq again,” said Michele Flournoy, a former senior Obama administration defense official. But, she said, “Particularly given the flow of foreign fighters…this is a terrorist problem that effects, us and we have to take a more forward leaning posture.”

Gabbard, Kinzinger and Flournoy spoke on CNN’s “State of the Union;” Thornberry appeared on ABC’s “This Week.” McCain appeared on CBS’ “Face the Nation.”