The U.S. Armed Forces are considered the world's most powerful military. The military budget of the United States was US$693 billion in 2019, the highest in the world. In 2018, that accounted for 36 percent of the world's defense expenditures. The U.S. Armed Forces has significant capabilities in both defense and power projection due to its large budget, resulting in advanced and powerful technologies which enables a widespread deployment of the force around the world, including around 800 military bases outside the United States. The U.S. Air Force is the world's largest air force, the U.S. Navy is the world's largest navy by tonnage, and the U.S. Navy and the U.S. Marine Corps combined are the world's second largest air arm. In terms of size, the U.S. Coast Guard is the world's 12th largest maritime force. The U.S. as of FY2019 has about 14,061 aircraft in its military inventory. The U.S. Space Force is the world's first and, as of 2021, only independent space force.