

The EU is comprised of sovereign entities, but those entities have chosen to give up certain competencies to the Union for various benefits. The EU already handles trade diplomacy and monetary policy through democratic institutions; it isn’t that hard to imagine that could also take on competencies related to defense.
The EU also could share the competency of defense with the various nations. After all, there are other countries which have sub national entities that have their own militaries.







China may not be perceived as a military threat, but it is credibly an economic threat. China is returning to a state where Europe has difficulty conducting trade with China as China will only accept natural resources for trade. That can be dangerous for an economy with a large safety net and declining productivity.