Is it possible for the U. S. to not only stay out of European affairs, but also the affairs of all other countries today? Explain and defend your opinion. (Do not focus your answer on trade.)

Today it is not possible. Since you can't talk about trade, you can talk about culture. The United States are a major export of culture throughout the world, which includes things like movies, music, books, and similar. These works of art often depict traits of the American culture and they are appealing to numerous people worldwide. Even if the US wanted to end all connections to Europeans and other countries worldwide, the culture would still carry on and keep spreading because people worldwide want it to spread.