|Interplanetary Strategic Alliance|
|Killzone, Killzone: Liberation, Killzone 2, Killzone 3, Killzone: Mercenary, Killzone: Shadow Fall|
|Planet||All UCN Colonies|
As new interplanetary colonies grew, the UCN discovered the lack of effective long-range communication caused gaps in the ability for the United Colonial Army to provide efficient defense throughout their vast colonized star systems. To rectify this problem, the UCN organized the Interplanetary Strategic Alliance, a military entity that allowed individual colonies the ability to integrate defensive capabilities to their specific requirements as well as enjoy full partnership in a unified defensive alliance of multiple colonies.
Colonial administrations provide funding and manpower whilst the UCN provides the training, equipment, and full political support for all of the interplanetary colonial administrations. The ISA acts as the main policing and defensive body for the citizens, and the main revenue gathering party for the local government. Each ISA command is directly subordinate to local colonial governmental authority, which in turn is subordinate to the UCN interplanetary authority.
Since each ISA Command is an independent unit of each colony, it is not directly linked to the military command of the UCN. As a result, the ISA Command's budget and strength are determined by the funds each local colonial administration provides. By 2133, ISA Altair and ISA Alpha Centauri were established.
Since ISA forces vary by the colonies they protect, the quality of technology within them differs. ISA Alpha Centauri for example heavily relied on static planetary defense systems and localized security. During the start of the Second Extrasolar War, the Helghast overwhelmed the colony of Vekta as a result.
However, as the war progressed and more aid came from the UCN, ISA Alpha Centauri became a more powerful force. Powerful cruisers, such as the Gray Deceiver, indicated a radical swing toward offensive might.
- First Extrasolar War
- Arcturus Insurrection
- First Vektan War
- Beta Hydri System Campaign
- Procyon Campaign
- Delta Pavonis Unrest
- Omicron Eridani Dispute
- Sorin Dispute
- Second Extrasolar War
- ISA Alpha Centauri is located on planet Vekta in the Alpha Centauri system. They are noted for their ongoing feud with the Helghast, as well as the fact that they have ignored the UCN's direct orders on several occasions without repercussions.
- ISA Altair is located on planet Gyre and was one of the first ISA Commands established. Not much is known about them, but it is possible that in 2390 the local ISA was called in to deal with the riots of the Helghast Workers Union Party. Given that the party later overthrew the Vektan-backed government, it is unclear what will happen to them or if the new government will last at all.
- In Killzone 2 multiplayer, when playing as an ISA soldier, the HUD is displayed in a light-blue color unlike the campaign.
- The ISA logo looks highly similar to a commonly-used symbol in other games. It most resembles a sideways version of the symbol from the Marathon game series or the Tau symbol from the Warhammer 40,000 franchise. It most likely represents the relationship between Earth and the colonies, imaged by how the Moon "Revolves around the Earth".
- The ISA logo looks incredibly similar to the logo of the 91st Reconnaissance Corps from Star Wars, albeit flipped on its side.