American mercenaries, hired by the UAE to kill in Yemen, have spoken candidly on camera for the first time in an investigation by BBC Arabic. At a time when Houthi attacks on Red Sea shipping have highlighted the international dimensions of the Yemeni conflict, the investigation also reveals how US mercenaries trained Emirati officers to kill the UAE’s political enemies in Yemen. These extra-judicial killings, conducted in the name of counter-terrorism, started in 2015 and continue to this day. Subscribe here: http://bit.ly/1rbfUog For more news, analysis and features visit: www.bbc.com/news #Yemen #BBCNews