Daniel Allen , who briefly served as Arlington-based CACI International ’s chief executive before being replaced earlier this year, will accept a reduction in severance from his former employer to take the top job at Reston-based Serco.

Allen was entitled to a $1.6 million lump sum payment in connection with his departure; the modification cuts that figure to $1 million, but allows him to take a new job that he previously could not under his noncompetition agreements, CACI said in a filing with the Securities and Exchange Commission last week.

“However, both Mr. Allen and his new employer have agreed that Mr. Allen must completely recuse himself from certain activities that might be competitive with CACI, until March 20, 2015,” the filing added.

Reston-based Serco, a subsidiary of the British Serco Group, said last week that Allen will become its chairman and chief executive, effective Dec. 15. Ed Casey , the current chief executive, has been named chief transformation officer at Serco Group.

Thales Communications changes its name

Clarksburg-based Thales Communications, a division of the Crystal City-based Thales USA, said last week that it is changing its name to Thales Defense & Security to better represent what it does. (Thales is a French defense, aerospace and security company).

The new organization brings together existing Thales units as well as recent acquisitions Tampa Microwave, Visionix and InterSense, the company said in its announcement. The name change is meant to demonstrate the company’s moves into expanded technology and adjacent markets.

Beyond its Clarksburg headquarters, the unit has facilities in California, Florida, Illinois, Kansas, Massachusetts, New York and Pennsylvania.

DBT-Data adds data center

Real estate investment and development firm DBT-Data, which has four data centers in Ashburn, has added to its portfolio a Harrisonburg-based data center, the company is set to announce Monday.

The 13-acre Cyber Integration Center, as the Harrisonburg facility is known, will bolster the company’s ability to serve both the federal government and private companies, a company official said in a draft announcement.

Lockheed cuts 600 employees

Lockheed Martin’s District-based Mission Systems and Training unit will cut about 600 employees nationally to adjust to increased competition and uncertain funding, a company spokesman said last week.

The spokesman said Lockheed will notify affected employees Nov. 6, but he expects the number affected locally to be fewer than 20.

The Bethesda-based contracting giant has been regularly trimming its payroll as government spending declines. A company spokesman said Wednesday that while the federal government shutdown has affected its business, these cuts are “independent from that event.”