The late 1800s was also a time of increasing globalization. It was exactly that interconnectedness that turned a local conflict into WWI.

Interconnectivity by trade before WW2 was very brittle, because everyone involved had to fend for their own trading routes. The pillar of today's globalisation is that big and middle powers don't have to roll their own security policy just to keep their own commerce running. The global naval hegemon has been doing that for them for decades now. The moment this goes away, we will suddenly see a whole lot of regional disputes popping up. "Safety" inspections for container ships of the competition or more blatant interference using drones. Once a precedent has been set of the US not stepping in, it can turn wild pretty fast.

That depends on how you define peace. Many non-Western nations are not at all at peace with the idea of their cultures being displaced and destroyed through the cultural imperialism of the US. And our dominant economic role and continued push for globalization is widely seen as the largest factor in that.

Many people in the West don't make that connection because our consumption of media is very insular. But it's been bubbling under the surface for awhile and now it's starting to boil over.