I'll try to keep my sentences shorter for you. :-)

It's not that 'wars must end, otherwise they keep fighting', but that there is 'a political settlement which satisfies enough participants to create stability ... otherwise they keep fighting'. [0]

I will stipulate that the sentence could have parsed more clearly. :-(

[0] It's just Clausewitz, effectively: Warfare is politics conducted by other means.

I think that was intended to be read as "how all wars must end" rather than "because all wars must end".