US Senate on Monday voted to confirm Jeh Johnson, a former top Pentagon lawyer, to be the secretary of homeland security.

Johnson was approved by a vote of 78 to 16 to succeed Janet Napolitano.

President Barack Obama nominated Johnson to lead the Department of Homeland Security in October. Johnson served as Pentagon general counsel from 2009 to 2012 during the first Obama administration.

Johnson played an important role in repealing "Don't Ask, Don't Tell" policy, which prohibited gays serving openly in the US military. He was also a central figure in devising a host of counter-terrorism policies, including the use of weaponized drones to target terrorist suspects.

The missions of the Department of Homeland Security include preventing terrorism and enhancing security, managing the US borders, administering immigration laws, securing cyberspace and ensuring disaster resilience.