The remnants of nations in the South-East corner of the globe (Indonesia, Malaysia, Philippines, Papua New Guinea, Australia and New Zealand) came together for safety. Eventually, a community was formed and farming was re-established. The Union then liberated some of the south eastern nations from the Indo-Madagascarean Republic. Over the years this community went undetected by the aliens and eventually formed its own defense units. When other nations went to war against the aliens, the Union of South Eastern Nations joined the fight and after many years, the humans emerged victorious. After the war, the nation shortened its name to the Pacific Union, although it's old name is still in use.
At one point the Union of South Eastern Nationsand built a powerful navy. Over the years, an Air Force was established, and although the union never created a powerful land army, but it won the war due to its superior naval and aerial capability and assault.