Story highlights U.S. officials have acknowledged that the training of rebels has fallen short

Monitoring group says at least 75 fighters are now north of Aleppo

(CNN) At least 75 fighters trained by U.S., British and Turkish forces have entered northern Syria, a monitoring group said.

The fighters crossed over from Turkey on Friday and Saturday and are now located in areas north of the city of Aleppo, said the London-based Syrian Observatory for Human Rights.

Their arrival comes shortly after U.S. officials acknowledged that the Pentagon's program to train and equip moderate Syrian rebels to help fight ISIS had fallen far short of its original aims.

A top U.S. general told the Senate last week that of the thousands of fighters the U.S. military was supposed to train in the first year, only four or five remained in place on the battlefield.

In light of the stark shortcomings, the Pentagon is expected to carry out a major overhaul of the training program for the rebels.

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