If only peace was ever lasting...

The peace lasts as long as you are willing to engage in war.

The US has been at war for decades.

These were 'interventions'. When you can bomb somebody and but there is no credible thread that your own population can be bombed back then it's not really a war. Your population doesn't feel the 'heat' and will not accept any inconveniences of ramping back domestic production

That makes WWI an intervention. Not saying you're wrong.

for the US WWI was indeed just an intervention, an unpopular one, at least initially, too.

Down voters fact checked me turns out Oceania had always been at war with Eurasia, sorry guys.

The threat of War is often good enough. Also we may not have another hot war, but it seems increasingly likely that we will see another cold war in the near future.