But the Japanese regime did want war. They invaded to Korea and Manchuria to 'protect' them from colonial powers, well knowing that that was exactly what they were themselves. Unless you buy into their propaganda, but I don't think any reasonably intelligent person ever has. The envisioned greater Japanese empire certainly wasn't going to come without one.
They thought they could force a peace after a quick campaign in the pacific, but that's how wars go, easy to start, not so easy to end.