The EU still has more soldiers, tanks, planes and so forth then Russia, even without the US. The reason to increase military spending is mainly to make sure Russia does not attack, as that would be even more expensive.
At the same time talking about capabilities is important. However there also needs to be a discussion about potential threats. For example the EU imports nearly all of its fossil fuels, mainly from countries it does not like too much. So reducing fossil fuel consumption might be a better investment, then military spending for some foreign mission. Similar story with China and manufacturing.
Or both, military spending because there is a war in Europe, more renewables (I think nuclear is late to the party, and we import the fuel from not the nicest countries too) so that we can phase out lots of oil, coal, gas consumption.
The time to act was 8 years ago. It was obvious from Trump’s first day in office that US withdrawal was going to be on the table, and possibly even the chance of US hostility if democratic institutions were to fully collapse. Europe probably isn’t looking at an actual invasion from anyone in the near future, but their global interests are looking extremely vulnerable right now, and its their own fault as much as it is the fault of American voters.
