If the UEF have had a militaristic policy similar to the GTVA, and had the Ubuntu ideology not been deemed a threat to the survival of humanity, the GTVA most likely would have started negotiations on a pacific reintegration of Sol into the GTVA, integration of the UEF's fleet into the GTVA navy, a share of Sol's industrial power, and negotiations on a solution to the economical crisis the GTVA is facing.
The Elders are negotiators. They'd have come to an arrangement.
As a bonus, civilians can go back and forth to their home system, families are reunited, the GTVA can go back to prepare for their unavoidable doom, and all is well.