The 2K Games blog offers details on Hangar 6 R&D DLC for The Bureau: XCOM Declassified that will be released on October 8th as a prequel for the XCOM prequel (thanks Eurogamer). Here's a bit:

Delivering a tactical, tense, and rewarding experience meant cranking up the difficulty. Yes, it's even more difficult than The Bureau, and equally as rewarding! But don't despair - we gave you lots of goodies to play with. DaSilva’s got a new series of powers and perks based on his “plant and trigger” bomb abilities in the level "Signal from Beyond." You can choose between those and some of Carter's old standbys in your upgrade path. There's enough experience to level up a couple of agents of every class, so you can mix and match and see what combo is really your style. Ammo and weapons are plentiful – including a new AK-47 and a prototype Microwave Gun that cooks enemies from the inside out. We wanted you to be able to maximize your mastery of third-person tactical XCOM combat while having the opportunity to try something new.