When Defense Secretary Ash Carter told the Senate Tuesday that the U.S. has trained only 60 Syrian moderate rebels so far to fight the Islamic State of Iraq and Syria, the low number wasn't news. Pentagon press had reported for weeks the total trained was under 100. The news was those total numbers had dropped even further.

"I know we had said earlier [that] 90 was the number that had started," said Pentagon spokesman Navy Capt. Jeff Davis, in his first official briefing with reporters. "As you heard the secretary say yesterday, the number is around 60. There has been attrition, absolutely."

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Davis said the program continues to face challenges getting recruits completely through the stringent vetting process run by Maj. Gen. Gen. Michael Nagata, head of special operations forces in the Middle East.

On Monday at the Pentagon, President Obama said the U.S. needed to increase its efforts to train Syrian rebels.

"I made it clear to my team that we will do more to train and equip the moderate opposition in Syria," Obama said.

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However, the Pentagon on Wednesday indicated that there would not be a change in the level of effort, due to the risks of clearing and training a fighter who might later prove a risk to U.S. personnel or strategic goals.

"This is the more, this is it," Davis said. "Right now we are committed to doing this program. We're not going to rush this program. This is more important that we have the quality and caliber of people more than it is about the speed or the numbers."