What Will Happen When the United States Withdraws from Syria?

Up until now, I supported almost everything President Trump has on his agenda upto 2020 when we elect the President of the United States again. He reduced unemployment to a rate we have never seen in the last 50 years. Yes, underemployment is down, as well. However, I never realized that a part of his agenda, we would have the potential to create additional terrorist acts either in the United States or against US interests abroad.