Will the members truly be willing to goto war (even nuclear war) to enforce the agreement? Unless the entire planet believes that whole heartedly the pact is meaningless.
I have my doubts, without the US NATO is largely toothless IMO.
The credibility question cuts both ways - a Trump-compromised NATO isn't more reliable than a European alliance with clear democratic commitments and mutual interests.
France and the UK already maintain a credible nuclear deterrent. European industrial capacity dwarfs Russia's. The EU's combined GDP exceeds China's. Scale isn't our problem - political will is.
Sweden indeed shows how principled positions can be maintained while building serious defense capabilities. Now multiply that model by Europe's combined industrial and technological base.
The ICC point is crucial - when most nations accept international law, continuing to accommodate "exceptionalism" becomes a weakness, not a strength. An alliance of genuine democracies, bound by shared values and mutual accountability, may prove more reliable than one held together by mere convenience.
Rather than asking if Europe can afford to build this capability, perhaps we should ask if we can afford not to.
I have my doubts, without the US NATO is largely toothless IMO.