SOUTH BEND, Ind. (AP) _ AM General says it plans to lay off 400 employees at its military assembly plant in northern Indiana beginning Jan. 1.
 
  Company spokesman Jeff Adams tells the South Bend Tribune that the layoffs announced Thursday will last until March.
 
  Adams says such temporary layoffs may become more common in the future. He says the company had hoped to have a new international contract ready for 2013, but it has been delayed.
 
  Workers at the Mishawaka plant that makes Humvees for the military had returned to work Nov. 26 following a layoff of nearly two months.