The US is to end its efforts to train new Syrian rebel forces and says it will shift to providing equipment and weapons to existing forces.
Its $500m (£326m) programme was heavily criticised after it emerged that US-trained rebels had handed vehicles and ammunition over to extremists.
It emerged last month that only four or five of the fighters were in Syria.
The programme had aimed to train and equip 5,400 fighters this year and a further 15,000 in 2016.
A senior administration official said the programme was being put on “pause” and said it could be restarted in future.
The programme had suffered from “significant challenges”, the official said, adding: “We had a very high bar in terms of recruiting”.
The US will no longer vet every individual recruit but just the leaders of the groups they decide to work with, who will face “very vigorous vetting”.
