Which of the following is considered the newest branch of the U.S. military?

The Space Force is recognized as the newest branch of the U.S. military, having been established on December 20, 2019. This service branch is dedicated to operations in outer space and is focused on developing military capabilities in space, securing U.S. interests in that domain, and organizing, training, and equipping personnel for space missions.

This designation as the newest branch reflects the evolving nature of warfare and the increasing importance of space as a theater of operations. The establishment of the Space Force underscores the U.S. government's commitment to maintaining a strategic advantage in space technology and capabilities.

In contrast, the Coast Guard, Marines, and Air Force have been established for much longer, with each having a distinct history and vital roles within the military structure of the United States. Thus, while all branches contribute significantly to national defense, the Space Force's recent origin makes it unique in this context.