Unfortunately, Ron Paul is a Rockwellite. Though all libertarians oppose rolling out the military for gratuitous wars (Korea, Vietnam, Kosovo), the Rockwellites also oppose war in retaliation for a direct attack, such as 9/11 and WW II. Yes, they are against American involvement in WW II.
No, they aren't against fighting defensive wars.
They do see that war is the 'health of the state' and always increases its size while decreasing individual liberty in the name of security.
Those 'suspended' liberties are very often never returned after the crises of the war has ended.
The Democrats wanted to keep war-time wage and price controls on after WW2 ended.