Raytheon Co.’s Integrated Defense Systems unit in San Diego received a $38.5 million U.S. Navy contract modification, the Navy announced on Dec. 11.

The deal covers work on the Ship Self Defense System Mark 2 for aircraft carriers and amphibious ships. Some 90 percent of the work will be performed in San Diego, and work is expected to continue for one year. The Naval Sea Systems Command of Washington, D.C. awarded the deal.

Raytheon (NYSE: RTN) is based in Massachusetts and had $23.7 billion in 2013 revenue.