Republicans and Democrats lambasted the Obama administration's strategy to combat the Islamic State group after a top U.S. general admitted that just a handful of U.S.-trained Syrian rebels are still on the battlefield fighting the militants.

The four or five fighters still engaged in the campaign is astonishingly short of the U.S. goal to train and equip 5,400 rebels a year at a cost of $500 million.

"That's a joke," said Sen. Kelly Ayotte, R-N.H.

Sen. Jeff Sessions, R-Ala., said: "We have to acknowledge this is a total failure. I wish it weren't so, but that's the fact."

After the first 54 were sent in to fight in July, a Syrian affiliate of al-Qaida attacked the group, killing several and taking others hostage while many fled. Asked how many remain, Gen. Lloyd Austin, commander of U.S. Centcom, which oversees the war effort, told the Senate Armed Services Committee: "It's a small number. ... We're talking four or five."

Christine Wormuth, undersecretary of defense for policy, said the U.S. currently was training more than 100 fighters, then later in her testimony said more specifically the number was between 100 and 120.

"If we get to the end of the year with us bragging about the difference between a 100 and a 120, it's time for a new plan," said Sen. Claire McCaskill, D-Mo.

One of the problems has been that many Syrian fighters want training and equipment to fight the government forces of Syria President Bashar Assad, but the U.S. program is limited to rebels who agree to only battle the militants.

The stunning admission from Austin came as defense officials scrambled separately to respond to allegations that they skewed intelligence assessments to give a rosier picture of conditions on the battlefield.

Austin said he would take "appropriate actions" if an investigation by the Defense Department's inspector general finds that senior defense officials altered intelligence to exaggerate progress being made against the Islamic State group and other militants in Syria.

McCaskill pointedly asked Austin to make sure the analysts who came forward do not face punitive actions.

"I will assure you that we will do everything that is in our power to ensure that the whistleblowers remain protected and there is no retaliation," Austin said.

The Obama administration was already struggling to defend its military strategy to "destroy and degrade" the terrorist group with an air campaign and programs to train, assist and equip local forces. Lawmakers and Republican presidential candidates have assailed the administration, contending that it has had limited or no success in fighting the militants.

Austin told committee members that the U.S. was looking at better ways to deploy the Syrian forces and predicted that it would take years to defeat IS and to restore stability in Iraq and Syria. Austin maintained the operation was making progress and said the military had always insisted the campaign would take time.

"Our partners, not us, are in the lead. It is taking a bit longer to get things done, but it must be this way if we are to achieve lasting and positive effects," Austin said.

The Pentagon also made it clear that U.S. military troops have done no training in Syria. Instead, U.S. special operations forces work with Syrian troops outside the country, including across the border in Iraq.

Sen. John McCain, R-Ariz., chairman of the committee, called the program a failure, outlined his vision of a U.S. strategy to fight IS and suggested that more American servicemen and women might eventually be needed.

"We need to help establish safe zones inside Syria where refugees and displaced people can be secure," McCain said. "We need forward air controllers to add precision and lethality to our air campaign. ... While no one believes that we need to invade Iraq or Syria, the fact is that we will likely need additional U.S. special forces and military advisers to be successful."

Austin said he would not recommend a buffer zone at this time. He said it would take a ground force to protect refugees in such a zone. "I don't see the force available to be able to protect them currently," he told McCain.

Other senators, including Sens. Tim Kaine, D-Va., and Angus King, I-Maine, said they agreed with McCain and urged the administration to consider a humanitarian zone to help protect Syrian refugees in their homeland and ease current exodus of Syrians to Europe and nations in the region.