Identifying the appropriate level of spending is difficult and there is not really any science about this. This is because different considerations play a role, including military strategy to political psychology.

The latest European Defence Industrial Strategy outlines a commitment to support investments by Member States and the European defence industry in the development and market introduction of cutting-edge defence technologies and capabilities. 

EU firms should be able to satisfy a large share of the increases in defence expenditure that are required immediately to support Ukraine and also those in the medium and longer-term

The EU-sponsored Eurobarometer polls routinely estimate support for EU defence integration between 70% and 80% of respondents, while a recent poll by the independent Bertelsmann Stiftung polling branch, Euopinions, returned a 87% support level. However, the devil is in the details: what is meant by “European defence policy” can wildly differ between people, and these simple questions present no trade-offs.