The Nuclear Ecosystem Drone Defense Act aims to provide the Secretary of Energy with specific exemptions regarding unmanned aircraft systems (UAS) originating from certain foreign entities. It amends the National Defense Authorization Act for Fiscal Year 2024 to exempt the Secretary of Energy from existing prohibitions on the procurement , operation , and use of federal funds for such UAS. These exemptions are intended to allow the Department of Energy greater flexibility in its operations. Additionally, the bill grants the Secretary of Energy new authorities concerning these UAS. It allows the Secretary to determine the usage of classified tracking for unmanned aircraft systems and provides an accounting exception for the Department of Energy. Crucially, the legislation expands the Secretary's authority to protect nuclear facilities and assets from UAS threats, specifically broadening the definition of covered facilities to include those involved in special nuclear material or non-nuclear components for weapons.