The YSE-IAC Cold War is an ongoing state of political and military tension between the Yamatai Star Empire and Iromakuanhe Astral Commonwealth, that started in late YE 36.

Although the races made official contact only at the International Relations Conference of YE 34, relations in the wake of the Second Mishhuvurthyar War were warm. The Commonwealth was one of the major contributors to Yamatai in in terms of food aid and Yamatai provided the Iromakuanhe with NMX technology in order to better protect themselves against their forces and modernize their ship production.

The bedrock of this agreement was shaky, as the Freespacer Massacre and Related Battles was public knowledge for years before first contact. Prior to the 2nd IRC and the opening of diplomatic channels, public concerns over the possibility of an invasion ran high due to lack of knowledge about the nature of Yamataian governance and society.

The possibility of hostilities emerged when large numbers of civilian volunteers from the Iromakuanhe homeworlds joined the Independent Worlds League as combatants and support personnel. Although the Commonwealth's government has no interest in open war, those aware of the foreign fighters suspected that this was a cynical move to support forces that could destabilize Yamatai and limit the possibility their ability to wage war on neighbors by bogging them down with proxies and guerrillas. Support for the organization was rescinded in YE 35 after their activities turned out to be little more than petty terrorism and morale among the volunteers dropped. In YE 36, the Commonwealth declared the IWL an illegal organization and actively began to pursue members operating within its borders, while quietly repatriating those who had abandoned the cause.

Concern of a war with Yamatai flared with the incident at Asura III and the creation of the operational plan QUIET RAGE by the YSE's military leadership. Although the Iromakuanhe have apologized, they have made no further diplomatic overtures in the uncertain climate that followed the incident and have begun planning for the possibility of a direct incursion on their homeworlds by the Star Army of Yamatai, sending units such as the VIA 333rd Special Task Force to Yamatai space and mobilizing extant forces like Operation Seigan.

What looms is an era of civil uncertainty and covert warfare…