In a vacuum libs are for peace ("rules-based international order") and reactionaries are the ones openly calling to act like an empire (Ted Cruz's comment on "let's find out if sand can glow"). When the wheels hit the pavement they act about the same, but they view themselves differently, justify imperial actions differently, and respond differently to hypotheticals.

But libs have been exposed to the same pro-military propaganda as everyone else, and let's be honest, a lot of military gadgets are pretty fucking cool, so they're shamelessly horny for a just war. Convince them the current war is actually a clear-cut good vs. evil struggle and they'll use the opportunity to cheerlead the military like they'd be embarrassed to in ~~Vietnam Grenada Iraq Panama Afghanistan Iraq again~~ one of those bad wars we've regretfully stumbled into in the past.