Yes. The President, as the Chief Executive, has the authority to manage anything w.r.t. foreign policy. This includes the imposition and management of tariffs (

Yes. The President, as the Chief Executive, has the authority to manage anything w.r.t. foreign policy. This includes the imposition and management of tariffs (something not a lot of people realize Congress ceded to the executive), as well as imposing sanctions, or getting any of the basket of regulatory agencies operating under him to enact something tut sweet. As far as I am aware, he added Semiconductor fab equipment to the restricted export list. ASML can, as a result, not sell those items to chinese customers without facing mucho pain from the U.S. in terms of sanctions or other unpleasantness. Anyone with U.S. citizenship who violates that restriction is in a great deal of hot water if it is found out about, and they try to return/are in the States.