Aliens just demanded our unconditional surrender

Did you ever watch Dark Skies? The old television show. The greys were controlled by a parasite that could infect a human host. The greys demanded our unconditional surrender. Majestic Twelve controlled everything. The reason I bring this up, has to do with the Eisenhower story from Tim Good's new book Earth An Alien Enterprise. The aliens were friendly. It just gets me wondering how many times aliens have interacted with Earth leaders. How friendly or hostile have those encounters been. Was Dulce a negotiation or an ultimatum?