Why did the united states increase the size of its navy

My answer is based on ww2 era and it was rivaled by japan because they had strong navy that rivaled the United States so they built more ships like the Uss Iowa which was built near the end of the war and it was deemed one of the strongest battleships and they created the navy in 1775 to protect the merchant ships from pirates. (i like the us navy)

The led the formation to the united states