Boeing is being hit with its second strike in less than a year after 3,200 hourly workers walked off their jobs building military aircraft.

About 3,200 union members at Boeing facilities in Michigan and Illinois went on strike at midnight on Monday after rejecting an offer from the company, the union said.

Roughly 3,200 workers are striking at sites in Missouri and Illinois. Members of the labor union representing the workers rejected a modified contract offered by Boeing last week.