Defense Secretary Ash Carter is pushing major changes to the Pentagon's personnel systems that are intended to attract the next generation of service members and drag the often-antiquated bureaucracy into the 21st century.

Many of the moves that Carter plans to outline in a speech Wednesday focus on how the Army, Navy, Air Force and Marine Corps recruit and retain troops.

For example, members of the military can begin investing in a 401(k)-type retirement plan beginning in January 2018.

Sabbatical programs will expand, and service members more easily can move from active duty to the reserves. That will give them a chance to take a break, seek advanced schooling, internships or other work and eventually bring that experience back to the Pentagon.