The negotiator even went as far as to say, "We hope to buy thrusters that can carry more energy and remain afloat in the high altitudes for an extended period."
Due to the rapid development of Z-wave technology, the initial 'Sky Fortress Plan' within the country was put on hold, as it became redundant, with no significance to constructing something that would not be used when it was more direct to build spaceships instead.
Now, the wealthy nations believe that anti-gravity fortresses in the air are very meaningful. They sent a negotiation team, hoping to purchase large anti-gravity devices and even requested to buy Z-wave weapons technology.
This request was directly rejected.