"If you want peace, prepare for war" is also one thing that you might want to consider. In other words, the improvement of new weapons technology can potentially reduce violent conflict - either by making people less willing to go to war with the possessor of those weapons, or by making the wars quicker and more decisive when they do break out. On the other hand, it doesn't sound very implausible to assume that wars getting quicker and more decisive will reduce the threshold for going to war...

Another point - I don't know how much influence the actual researchers working for those agencies have on the projects, but if you're working for them, there's a small chance that you'll get to influence their development towards more peaceful purposes. Like emphasizing the communication-enabling aspects of a new technology that could also be used for destruction, or something. Of course, gaining such influence would probably require a longer career for those agencies.