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.