Counter-terrorism training provided by American mercenaries to Emirati officers in Yemen has been used to train locals who can work under a lower profile - sparking a major uptick in political assassinations, a whistleblower told BBC Arabic Investigations.
The BBC has also found that despite the American mercenaries' stated aim to eliminate the jihadist groups al-Qaeda and Islamic State (IS) in southern Yemen, in fact the UAE has gone on to recruit former al-Qaeda members for a security force it has created on the ground in Yemen to fight the Houthi rebel movement and other armed factions.
The UAE government has denied the allegations in our investigation - that it had assassinated those without links to terrorism - saying they were "false and without merit".
The killing spree in Yemen - more than 100 assassinations in a three-year period - is just one element of an ongoing bitter internecine conflict pitting several international powers against each other in the Middle East's poorest country.
The deadly atmosphere has discouraged the permanent return of Yemen's internationally recognised government. This, it could be argued, has indirectly helped to embolden the Iran-backed Houthis - currently in the news for attacking ships and disrupting trade in the Red Sea. In recent days, Washington has announced that it will now re-designate the group as "global terrorists". [BBC]