A political argument rebutting an imagined accusation. The first clause uses the normative negation ~ものではない ('is not something one should / ought to X') — a moral-judgment frame, not just a factual 'is not.' The second uses ~わけではない ('it's not the case that X') to deny the inference that constitutional amendment equals war-lust. ~たくてしょうがない is a set pattern 'to want to X so badly one can't stand it,' where しょうがない ('can't be helped') intensifies the desire. Clauses linked by ~し, the 'and-furthermore' reason-lister.