The U.S. military is working on a complete overhaul of its mission to "train and equip" Syrian fighters, multiple defense officials told Fox News, after the embarrassing admission Wednesday that only "four or five" fighters from the program are on the battlefield today. 

Gen. Lloyd Austin, head of U.S. Central Command, made that admission in Senate committee testimony, acknowledging the U.S. would fall far short of its original goal of training 5,400 in the first year. Many of the few dozen trained to date have been killed or captured, or have fled, and Austin said: "The ones that are in the fight ... we're talking four or five." 

A senior military official now tells Fox News that, instead of training complete rebel units, U.S. Special Forces will drastically scale back the Syrian training program. 

No longer will the goal be to train 5,400 in a year. Instead, the aim is to train 500 "enablers" or "JTAC-like" troops (joint terminal attack controllers), who can embed with established groups fighting the Islamic State in Syria and give them the capability to call in airstrikes from U.S. military aircraft, the senior military official told Fox News. 

"No longer will batches of units be trained," the official added. "We just want to help established groups like the YPG be successful against ISIS."   

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The YPG is a paramilitary force composed of Syrian Kurds officially known as "People's Protection Units," which occupy northern Syria. 

The Pentagon spent $41.8 million (out of $500 million set aside for the training program) to vet, arm and pay the 54 rebels trained to date.  They were inserted into Syria in July, only to be killed, captured or scattered after they ran into the Nusra Front, Al Qaeda's Syrian affiliate. 

Some of the rebels also went home for the end of Ramadan and never returned. 

"It was some expensive kit we gave them -- dune buggies, M-16s, body armor, night vision goggles, helmets, boots," the official said, describing where some of the $41.8 million went. 

The cost of the program -- and its meager results so far -- have lawmakers skeptical about authorizing it again. 

At Wednesday's Senate Armed Services Committee hearing, Sen. Claire McCaskill, D-Mo., challenged the Pentagon's request for $600 million for more training next year. 

"We're counting on our fingers and toes at this point," she said of the trained fighters. 

Sen. Jeff Sessions, R-Ala., called it a "total failure." 

The Pentagon had hoped to train 5,400 Syrian rebels in a year, and 12,000-15,000 over the next three years, but Austin admitted Wednesday the U.S. military would fall short. 

"We certainly won't, at the pace we're going, reach the goal that we had initially established for ourselves," he told lawmakers.

Lucas Tomlinson is the Pentagon and State Department producer for Fox News Channel. You can follow him on Twitter: @LucasFoxNews