The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage of its active battle fleet alone exceeding the next 13 navies combined, including 11 allies or partner nations of the U.S. as of 2009. It has the highest combined battle fleet tonnage (4,635,628 tonnes as of 2023)[.