Harrisburg and Lancaster sites were included in a $592 million contract for Maryland-based defense and aerospace manufacturer Lockheed Martin Corp. to work on missile systems for the U.S. Strategic System Programs, according to the Department of Defense.

Lockheed Martin builds submarine-fired Trident II D5 fleet ballistic missiles and support systems under existing contracts, according to the DOD.

The latest five-year contract is a modification of an older one and includes options for missile production and system support that would make its total worth nearly $1.1 billion, according to the DOD. If all options are exercised, work would continue until April 2018.

Both the Lancaster and Harrisburg sites will be working on less than 1 percent of the contract, according to the DOD. Most of the contract work will take place in California and Florida.

Lockheed Martin, based in Bethesda, Md., trades its shares on the New York Stock Exchange under the ticker symbol LMT.