Notice of the acquisition was issued Wednesday but details weren't revealed.
"With ACS, we are acquiring a technology company with a focus on cybersecurity, network communications and other leading-edge technologies key to critical infrastructure protection and optimization," said Bill Graham, president and chief executive officer of the SI Organization. "In light of the unique nature of much of ACS's work, acquisition by a U.S. owner will strengthen relationships with many U.S. government clients."
SI specializes in cybersecurity and information assurance, network and operations, data analytics, advanced software and methodologies, wireless and mobility, application engineering and integration, smart grid, and optical networking and quantum technologies for the U.S. intelligence community, Department of Defense and other agencies.
ACS' services, it noted, complements its own.
"Both our clients and our employees significantly benefit from this acquisition," said Brent Greene, ACS's chief executive officer. "In the SI, it is clear we have found a strong fit for our unique culture of innovation."
ACS, previously the research and engineering arm of Telcordia Technologies, was established last year as a result of government concern over Telcordia's acquisition by Ericsson of Sweden.