After the Government Accountability Office (GAO) in early October rejected a protest by Northrop Grumman [NOC], Raytheon [RTN] has been work supporting a cyber security system operated by the Department of Homeland Security (DHS).

The GAO’s decision was rendered after DHS twice reviewed earlier awards of the $1 billion-plus DOMino contract to Raytheon before re-awarding the contract to the company. The decision cleared the way for Raytheon to begin working with the cyber threat detection and prevention systems, says Thomas Kennedy, Raytheon’s chairman and CEO, on the company’s recent third quarter earnings call.

DHS originally awarded Raytheon the contract to support the National Cybersecurity Protection System (NCPS) in Sept. 2015, but the award was protested by Northrop Grumman. DHS in turn decided to take corrective actions that led it in June 2016 to affirm the original award to Raytheon. Northrop Grumman again protested and again DHS decided to take corrective action although once again it decided to re-award the contract to Raytheon in June 2017.

After Northrop Grumman protested again, DHS held its ground, allowing the GAO to complete its adjudication of the award decision. The agency rendered its decision on Oct. 4 but didn’t publish its rationale until Oct. 19.

The Development, Operations and Maintenance (DOMino) contract supports the NCPS, which is better known as EINSTEIN, a platform that DHS uses to help detect and prevent cyber security threats from reaching federal civilian networks. EINSTEIN was originally supported by General Dynamics [GD] but the DOMino competition was a new program effort.

According to the GAO, Northrop Grumman protested the award to Raytheon for several reasons, including that the company had hired former DHS employees, giving it an edge in the competition, that DHS changed program requirements but didn’t revise the request for proposal, that evaluations of past performance by bidders weren’t reasonable, and DHS had “unequal discussions” with Raytheon.

On the challenge points, GAO says DHS’ own review “reasonably concluded” that its former employees that went to work for Raytheon didn’t have information that would give the company an “unfair competitive advantage.” On the matter of the changed requirements, GAO says it found no reason that there was a “material” change and that the RFP had to be revised.

GAO rejects Northrop Grumman’s concerns about Raytheon’s past performance, agreeing with DHS that the company’s work on related projects, although smaller, was sufficient to be evaluated for DOMino. GAO also disagrees with Northrop Grumman on the point of unequal discussions, pointing out that a missing form for one of Raytheon’s subcontractors in the bid process didn’t affect a security review of its proposal.