On a few occasions, I'd had soldiers become panicked, go berserk and generally be affected by the punishing situations they have to deal with. However, there were also times when individuals were affected despite being in a relatively secure position. This indicated a new form of alien attack, and my fears were confirmed once we'd researched the Sectoid brains and their Mind Probes.
It seemed the elite Sectoid soldiers, the Leaders in particular, had an amazing psychic ability. They used this to undermine the mental state of my soldiers, and in some cases even control their minds. I had to respond in kind, discovering the means of this attack and finding a way to protect my troops. First I had to capture one of their Leaders, to gain more information.
The breakthrough lead me to the discovery that humanity had a variable psychic ability, and it was clear that I would have to test and train my soldiers to find those which were most prepared to wage psionic war. This new weapon was of the highest priority, and I shifted all my resources to enable it's quick completion.
At the start of each month, I would send soldiers to the psionic training laboratory to discover their latent talent. Those with high abilities would continue training, whilst those without would be relocated. For the final assault I wanted a full roster of well trained personnel, able to withstand all that the aliens could muster.
I also built a set of Psi-Amps, with which these soldier could focus their new-found abilities on the battlefield. The ability to control alien minds could be essential in turning the tide against the alien menace!
Knowing I was close to my goal of assaulting the Alien Headquarters on Mars, I have also began a series of base constructions to fortify and protect my bases. Grav shields and plasma defences were first, to enable repulsion of enemy craft. Also, after fully researching the psychic nature of the aliens, I could also create Mind Shields that would help protect my bases from ever being detected by prying alien minds.
Now, with the Avenger spacecraft complete, and my soldiers training for the final assault, all I need is a little Elerium, and a lot of luck.