While Turkey sees the PYD and YPG as offshoots of the banned PKK, the US does not and believes they are the only effective force against IS on the ground in Syria, reports the BBC's Mark Lowen in Istanbul.
https://www.bbc.co.uk/news/world-middle-east-35541003
Em 2014 e 2015, os EUA iniciaram operação para lançar 120 toneladas de suprimentos militares para o YPG, as YPG também receberam 27 pacotes totalizando 24 toneladas de armas pequenas e munições e 10 toneladas de suprimentos médicos.
"U.S. military cargo planes gave 50 tons of ammunition to rebel groups overnight in northern Syria, using an air drop of 112 pallets as the first step in the Obama effort to find new ways to support those groups
All pallets successfully were recovered by friendly forces, a U.S. official said."
https://edition.cnn.com/2015/10/12/politics/syria-rebel-groups-ammunition-50-tons/index.html