Wisconsin-based Oshkosh Corp. said it will lay off 450 workers in its defense division starting in January.
Company spokesman John Daggett said decreasing workloads for defense contracts as the Iraq and Afghanistan wars wind down are the reason.
Oshkosh will make the cuts over a three-week period starting Jan. 11, 2013.
In a statement, Oshkosh said it will work with laid-off employees to help them make the transition to other employment.
Union leaders said they're looking into ways to lessen the impact of layoffs, such as by allowing some employees to retire early.
Oshkosh manufactures military vehicles as well as trucks and other special-purpose equipment. WLUK-TV reported that after the layoffs, Oshkosh will still employ 3,500 defense employees in the town of Oshkosh.