Why has the U.S. been so feared and respected since World War II?

The U.S. doesn't tend to start big wars but we also tend to finish big wars in really horrific ways.

At the end of World War II the U.S. firebombed Germany and Japan to get them to surrender which burned up cities like Dresden and Tokyo and others. When Japan wouldn't surrender after firebombing and burning to the ground many of their cities we nuked Hiroshima and Nagasaki. This saved the lives of about 1 million American Soldiers doing this.

However, it also has horrified the world because this made us still the ONLY nation to have nuked another nation.

Was this good or bad?

Is it good for every nation on earth to be that terrified of any other nation this long?

I don't think I can properly answer this question at this point.

However, it did provide the basis for the United Nations and a new World Order that still somewhat exists today 71 years later.