In addition to the tech requirement to purchase, in order to use the EMP wonder do I have to maintain 5000 tech?
"EMP Weaponization - $200,000,000 + (Nation Strength * 2,000) - Provides attackers with 5,000 or more technology the option to launch a targeted EMP nuclear attack. Nuclear weapons can target higher infrastructure, higher land, or higher technology damage based on player choice when launching nukes. When you choose to target infrastructure, land, or technology you are trading more damage to your target for less damage for the other two. For instance, if you choose to target infrastructure you will do more base damage to infrastructure but less damage to land and technology. Requires 5,000 technology and a Weapons Research Complex to purchase."