The White House and Pentagon acknowledged Friday that the U.S. “is at war” with the Islamic State -- contradicting Secretary of State John Kerry and others who a day earlier refused to use that term, prompting criticism from lawmakers that the administration was downplaying the conflict.

White House Press Secretary Josh Earnest and Pentagon spokesman Rear Adm. John Kirby used almost identical language when pressed by reporters Friday whether or not the expanded military operation against the terrorist group is in fact a war.

“In the same way that the United States is at war with Al Qaeda and its affiliates … the United States is at war with ISIL,” Earnest said.

Kirby said “this is not the Iraq War” from a decade ago, “but make no mistake -- we know we are at war with ISIL in the same way we are at war and continue to be at war with Al Qaeda and its affiliates.”

The comments are a sharp turnaround from how Kerry described the military operation on Thursday. In interviews with CNN and CBS News, Kerry described it as a “very significant” and “major counterterrorism operation.” He told CBS News that “war is the wrong terminology.”

His spokeswoman, Marie Harf, also said she would not “refer to our efforts” as part of the “war on terrorism.”

Kerry’s comments, though, stirred confusion on Capitol Hill, coming a day after President Obama announced plans to expand airstrikes in Iraq and authorize them in Syria, while dispatching hundreds more U.S. military personnel.

Obama called for a coalition of nations to ultimately “destroy” the growing terror network. Meanwhile, the CIA confirmed that its latest estimates show the Islamic State has as many as 31,500 fighters across Iraq and Syria. That’s close to the estimated size of the Taliban force in 2001.  

Sen. John McCain, R-Ariz., and other lawmakers suggested Kerry’s comments did not square with Obama’s stated goal of defeating the vast terror network.

“It’s hard to find a response to that,” McCain told Fox News on Thursday night, when asked about Kerry’s comments. “Then what was the president talking about [Wednesday] night?” 

Kerry wasn't the only one having a hard time describing the mission on Thursday. National Security Adviser Susan Rice likewise told CNN on Thursday she wasn't sure whether it should be called a war or a "sustained counterterrorism campaign." 

Senior State Department officials stressed to Fox News on Friday that Kerry's comments were consistent with what other senior U.S. officials were saying at the time, and made clear that the secretary remains on the same page as the rest of the administration. 

"This was a deliberate, administration-wide adjustment in language," a senior State Department official told Fox News, "which Secretary Kerry would have also used today had he been asked." 

House Homeland Security Committee Chairman Michael McCaul, R-Texas, said earlier Friday that the semantics over what to call the operation “weakens the mission.”

“Words matter,” McCaul said. He claimed the administration was being careful with its language because the terror group defies Obama’s “campaign narrative” about ending the war on terrorism and putting Al Qaeda on the run.

“ISIL clearly hasn’t gotten the memo that I think John Kerry did,” McCaul said.

But in the Pentagon and White House briefings Friday afternoon, it appeared the administration was backing off the earlier characterization. 

Earnest clarified that the operation is not a case of the United States acting alone against the Islamic State, since the Islamic State, he said, is waging a war against the international community.

But he repeated that the U.S. is “at war” with ISIS as it is at war with Al Qaeda and its affiliates. 

Fox News' James Rosen contributed to this report.