<Table> <Tr> <Th_colspan="2"> Secretary of Defense of the United States </Th> </Tr> <Tr> <Td_colspan="2"> Seal of the Department of Defense </Td> </Tr> <Tr> <Td_colspan="2"> Flag of the Secretary of Defense </Td> </Tr> <Tr> <Td_colspan="2"> Incumbent Jim Mattis since January 20, 2017 </Td> </Tr> <Tr> <Td_colspan="2"> United States Department of Defense Office of the Secretary of Defense </Td> </Tr> <Tr> <Th> Style </Th> <Td> Mr. Secretary </Td> </Tr> <Tr> <Th> Member of </Th> <Td> The Cabinet National Security Council </Td> </Tr> <Tr> <Th> Reports to </Th> <Td> The President </Td> </Tr> <Tr> <Th> Seat </Th> <Td> The Pentagon, Arlington County, Virginia, U.S. </Td> </Tr> <Tr> <Th> Appointer </Th> <Td> The President with Senate advice and consent </Td> </Tr> <Tr> <Th> Term length </Th> <Td> No fixed term </Td> </Tr> <Tr> <Th> Constituting instrument </Th> <Td> 10 U.S.C. § 113 50 U.S.C. § 401 </Td> </Tr> <Tr> <Th> Inaugural holder </Th> <Td> James Forrestal </Td> </Tr> <Tr> <Th> Formation </Th> <Td> September 17, 1947; 70 years ago (1947 - 09 - 17) </Td> </Tr> <Tr> <Th> Succession </Th> <Td> Sixth </Td> </Tr> <Tr> <Th> Deputy </Th> <Td> Deputy Secretary of Defense </Td> </Tr> <Tr> <Th> Salary </Th> <Td> Executive Schedule, Level 1 </Td> </Tr> <Tr> <Th> Website </Th> <Td> www.defense.gov </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Secretary of Defense of the United States </Th> </Tr> <Tr> <Td_colspan="2"> Seal of the Department of Defense </Td> </Tr> <Tr> <Td_colspan="2"> Flag of the Secretary of Defense </Td> </Tr>

Who is the secretary of defense and what do they do