WASHINGTON, May 26 -- Critics fret the U.S. strategy in Iraqmay not be working, after Islamic State (IS) militants recently took the Iraqi city of Ramadi, casting doubt on whether the U.S.-led coalition can destroy the terror group.

IS several months ago swept through Syriaand Northern Iraq and overran vast swaths of territory, imposing draconian Islamist laws. Experts said the fall of Ramadi and the IS penetration of the defenses of the Baiji oil refinery have shifted the advantage in favor of the terrorists.

While U.S. President Barack Obama's strategy entails building capacity in Iraq's army, bombing IS targets and reconciling relations between Shiites and Sunnis, the latter has so far seen little success.

On Sunday, U.S. Defense Secretary Ash Carter said in an interview on CNN's "State of the Union" that Iraqi forces showed no "will to fight" in Ramadi, a city of Sunnis. What's more, Iraqi soldiers abandoned U.S.-supplied vehicles that are now likely being used by IS.

Iraqi troops "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 (IS) and defend themselves," Carter said.

Critics are also blasting Obama with what they said appears to be putting the issue on the backburner, with a recent speech in which he called climate change a threat to national and global security.

Republican Senator John McCain, a former presidential candidate and outspoken critic of Obama's IS policy, on Sunday criticized Obama for failing to produce a strategy of fighting IS. "There is no strategy, and anybody who says there is, I'd like to hear what it is," he told the CBS News.

"Meanwhile the president of the United Statesis saying that the biggest problem we have is climate change," said McCain, who is also chairman of the Senate Armed Services Committee.

Heritage Foundation's national security expert Steven Bucci told Xinhua that while weather and natural disasters are important issues, they are in no way the nation's highest security concern.

Critics also fret over the message Obama is sending to IS and other enemies worldwide as he appears to downplay the issue's importance. "Obama does not really have the focus and strength to adequately address the threat. His weak response will only continue to allow them to recruit more personnel," Bucci said.

"He speaks boldly but has little follow-through," Bucci added.

Media across the U.S. is blasting the current strategy as not working, with the Los Angeles Times on Saturday noting that "U.S. officials say the Iraqi government has budgeted money and weapons for 8,000 fighters in Anbar, the largest Sunni province -- but most of the aid hasn't been delivered."

While the White Houseearlier this month called the fall of Ramadi a setback, experts said that term is downplaying the seriousness of the issue. Rick Brennan, senior political scientist at the RAND Corporation, told Xinhua that the term "setback" underplays the significance of IS' tactical victory in Ramadi.

Obama has been hammered by critics for his earlier downplaying of the IS threat, which they said Obama appeared to put on the backburner until the threat became too great to ignore.

Washington's ultimate fear is another terror strike on the level of the Sept. 11, 2001 attacks on New York City and Washington, which killed nearly 3,000 people, and the U.S. wants to prevent IS from setting up its own state from where it could plan such an operation, much as al-Qaeda did in the lead-up to Sept. 11.

Indeed, IS has made threats against the U.S. Earlier this month, it claimed responsibility for a gun attack in the U.S. state of Texas.

The shooting marked the first time IS actually inspired or even had a hand in pulling off an attack on the U.S. soil, which indicates that it has breached the walls of U.S. security by using social media to galvanize its sympathizers to launch terror attacks.