Answer: Sanctions
Step-by-step explanation:
One of the ways the U.S used to control the activities of Iran as regards sponsoring or trying to sponsor terrorism is by placing sanctions on them. We all know the United States has a string influence in the world market and placing a sanction can affect Iran irrespective of how strong they may perceive to be. The United States have issued warnings to them severally regards this up to the extent of issuing a possible way if they persist with their actions.