Pursuing a defender agenda would mean refusing to authorize any invasion, not making it more difficult for invasions to be authorized.
I disagree. Many outright defender regions authorize invasions with political justification -- 10000 Islands come to mind as a current example.
Simply put a "defender" region is a region that supports and (actively or inactively) engages in the defense of founderless regions from arbitrary and unjustified invasions and likewise refrains from aiding, engaging in or supporting the arbitrary and unjustified invasions of founderless regions. The conduct of politically justified invasions is compatible with being a "defender" region.
Examples: 10000 Islands, Texas, The Rejected Realms, The Allied Republics.
A "raider" region is a region that supports and (actively or inactively) engages in arbitrary and unjustified invasions of founderless regions and likewise, refrains from defending any founderless region without political justification. The conduct of politically justified invasions is compatible with being a "raider" region.
Examples: Take your pick, The Black Riders, The Black Hawks, The Black Whatever and yes, The Cat Burglars (albeit without the same extent of damage caused to its victims).
A "centrist" region is a region that both supports and (actively or inactively) engages in the defense of founderless regions from arbitrary and unjustified invasions
AND the invasion of founderless regions for arbitrary and unjustified reasons. The conduct of politically justified invasions is compatible with being a "centrist" region.
Examples: Osiris (I believe they identify as 'independent'), The North Pacific (?), Taijitu (Grey Army is up, yes?).
An "independent" region
only supports and (actively or inactively) engages in any military conduct when it is politically justified and deemed necessary -- a deviation from this principle leads an 'independent' region to defenderism, raiderism and centrism. The conduct of arbitrary and unjustified invasions or defenses based on apolitical ethics is incompatible with being an "independent" region.
Examples: Equilism, The New Inquisition and Europeia (ideally the last two, but in practice they can both lean towards raiderism).
A "neutral" region is a region that does engage in military activity actively or inactively notwithstanding invasions and defenses that have trivial political consequences (i.e, warzones).
Examples: Wysteria, Europe, Absolution, The South Pacific (subject to change, I believe).