The Navy will face a $4 billion operations and maintenance cut in fiscal year 2013 if sequestration is triggered in March, forcing the fleet to stop all deployments to the Caribbean and South America and curb other movements around the globe, Chief of Naval Operations Adm. Jonathan Greenert writes in a memo. The new measures would come on top of steps the Navy is already taking to address the continuing resolution, including the cancellation of ship maintenance availabilities. "Unless Congress...