Those that speak of American power need to understand two key facts. The United States may be a strong country but it has never used its strength to dominate others. Unlike most of the other European and Asian nations, America has never wanted a foreign empire or had imperial ambitious. It is an American trait to free territories it has conquered in war including Cuba, the Philippines, Mexico, and even the entire nations of Japan and Germany. While kings and queens built huge armies and navies designed for world domination and territorial conquest, the United States actually purchased the land which built its country from France, Spain, Mexico, and even Russia.
America and its military forces have been called on time and time again to assist struggling nations with freedom loving values against tyrants who would take those precious rights away. These fights were not American fights but wars off in faraway lands. But the United States became the Arsenal of Democracy and the guarantor of world peace because no other nation had the strength, resources, but most of all the commitment to national values to take up the challenge.
Unlike most another European, Asian, African, and South American nations where border wars are common over territory disputes, the United States has had peaceful relations with its neighbors for generations. The military forces of the American people could overrun both Canada and Mexico in an afternoon if it was their choice but no such invasion was ever planned. Instead, America decided to live in peace with its neighbors and work towards mutual cooperation rather than gain through force and intimidation.
The United States is a powerful nation but uses its resources rarely, reserving the application of its might for only the most drastic circumstances such as when the nation was attacked at Pearl Harbor or on September 11, 2001. Without American strength and resolve there would be small wars across the planet from the Korean peninsula to the Balkans. It also goes without saying American military might is used for peaceful and humanitarian purposes too. When there is a natural disaster anywhere in the world the first responders almost always wear the uniform of the United States.