Work on Saturday

peace,
My brother was offered a job in the cyber operations department at a company that also develops weapons for the IDF. The operations department is responsible for protecting the company from cyber attacks. Such attacks also have security implications for the country's security indirectly. The job description includes working on Shabbat. On Shabbat, the number of attacks increases and most of the defense is carried out on Shabbat. The question is, is it permissible to work in such a job? How is it different from permanent service in an intelligence unit (where I assume it is clearly permissible)? Where do you draw the line in cases like this?
Thank you very much,