General Dynamics Corp., a Virginia-based company that makes weapon systems and combat vehicles as well as information systems, said Monday that it has agreed to buy Fidelis Security Systems Inc. as a way to beef up its cyber security offerings.

The value of the transaction is not being disclosed, General Dynamics said in a press release.

Privately held Fidelis Security Systems employs about 70 people. Its headquarters is in Waltham, and it also has a facility in Bethesda, Md. Fidelis Security specializes in helping its customers to prevent data breaches.

The acquisition has been approved by the boards of directors of both companies, said General Dynamics, which added that it expects the transaction to be completed in the third quarter.

Fidelis Security Systems will become part of General Dynamics Advanced Information Systems, a provider of intelligence, surveillance, and reconnaissance services, General Dynamics said.

There is no plan to transfer jobs from Waltham to Virginia, a General Dynamics spokesman said.