The USA is working with the Kurdish-led Syrian Democratic Forces (SDF) to create a border force, potentially 30,000 fighters, along the Turkey/Iraq borders and along the Syrian side of the Euphrates. Since 2014 it has led the coalition of nations using air strikes and specialist troops to fight IS across Syria and Iraq. IS has now lost most of that territory. For much of the war, the US and Turkey worked together against the Assad government. But this decision to back Kurdish fighters has enraged Ankara, and Syria denounced any new border force as an assault on its sovereignty, adding that Syrians joining the force would be ‘traitors’. Turkey vowed to ‘drown’ Kurdish border security forces in bullets, and Erdogan accused America of forming a ‘terrorist’ force on Turkey’s border. The fragile state of relations between the nations deteriorates.