The Aikhibba Imperium and the Valletta Commonwealth share a planet orbiting the secondary star of the Nullarbor system, directly adjacent to Sol.
Diplomatic overtures were made and we granted trade access to both, but only the Imperium reciprocated. Eventually, the Commonwealth turned hostile and destroyed several of our merchant vessels.
Since our offensive capabilities were missile-based and we had insufficient ammunition for a prolonged war, the high council voted to resolve the matter with a single overwhelming display of force. A convenient Lagrange Point allowed an intra-system jump that almost brought us into missile range, and since our missiles were considerably faster (30000km/s vs 12000km/s) we would be able to withdraw unengaged after making our displeasure known. Our battlefleet expended most of its ordnance in a volley of 252 missiles against Valletta population centers, overwhelming the surprisingly capable point defence and causing an immediate surrender.
The dispersed enemy forces appeared unlikely to overwhelm the newly acquired 5 Orbital Beam Bases with their combined 140 twin laser turrets, so the Missile Bases and AMM-armed escort vessels in orbit were used offensively against approaching ships, with breaks to thin out occasionally large volleys over 50 missiles (highest encountered: around 80). All in all, thousands of seized Valletta missiles were fired.
Some hostiles managed to close the distance to as little as 80k, but our new subjects held the line without coming under beam or point-blank missile fire. The immediate vicinity of the planet is clear, and while skirmishes will continue for a while, complete victory seems inevitable.
Planetary casualties are unknown, but we have acquired 790 million new subjects who will need to be pacified and cared for. Emergency housing and infrastructure projects are underway, as the nuclear winter with temperatures below -34°C is currently expected to result in millions of new deaths each month. This has to be balanced against the need for maintenance facilities, as the acquired orbital defences are in a woeful state of disrepair. Fortunately, the nation exhibits a high degree of industrial development - without the current disruption its industrial output would be higher than Earth's, with large mineral stockpiles and several times the shipyard capacity. Curiously, there is almost no educational or financial infrastructure.
The Aikhibba Imperium so far showed remarkable restraint, we haven't received as much as a protest note. Hopefully there will be no cause for further unpleasantness, the history books will likely be unkind to us as it is.