Mark Esper is the secretary of defense for the U.S. Department of Defense. President Donald Trump (R) nominated him to this position on July 15, 2019. The U.S. Senate confirmed him by a vote of 90-8 on July 23, 2019. He was sworn in the same day.
At the time of Esper's nomination, he was serving as acting defense secretary. He resigned upon being nominated, as federal law prohibits the nominee for defense secretary to serve in the role during the nomination process. Richard Spencer replaced Esper as acting defense secretary.
The secretary of defense oversees the military departments, the chairman of the Joint Chiefs of Staff, and the unified commands. According to the Department of Defense's website, "The military departments train and equip the military forces. The Chairman plans and coordinates military deployments and operations. The unified commands conduct the military operations."
Esper was the secretary of the United States Army from 2017 to 2019. He served on active duty for over a decade, after which he served in the National Guard and Army Reserve.
Esper earned a B.S. in engineering from the United States Military Academy in 1986. He received his master's degree in public administration from Harvard University in 1995 and his Ph.D. in public policy from George Washington University in 2008.