Question

Hello, 
My brother was offered a job in a cyber operations center at a company that develops weapons, including for the IDF. The operations center is responsible for defending the company against cyberattacks. Such attacks also have security significance, indirectly, for the country's security. The job definition includes working on the Sabbath. On the Sabbath the number of attacks increases, and most of the defense activity is carried out on the Sabbath. The question is: is it permissible to work at such a job? How is this different from career military service in an intelligence unit (where I assume it is obviously permitted)? Where do you draw the line in cases like this?
Thank you very much,