Do you know there were already many killing between Shia and Sunni Muslim basically as long as Islam exist, most of those casualty (Even today) were created by both Muslim group targeting one another. However, most of those were classified as sectarian violence, but not terrorism (which basically only after 2001)
While we should not denied the fact that US involvement worsen the situation, but one should not blame the US on something they did not start to begin with. And I do not see how this have anything to do with Xinjiang. There were many Muslim country that US involve with does not appear in this list (Indonesia, Saudi Arabia, Jordan and so on). So what does that say about the issue?