Showing a defensive force does not really need the USA at present, it all helps, but between UK, France, Spain, Germany, Italy, Sweden, Poland, Romania it is fair to say there is a huge force there alone, along with other potential countries strengthening defensive positions. I think the latter is more sensible, 100,000's of USA troops flying in is more likely to raise concern with Putin and all these EU countries have USA military bases which are manned anyway, so there is a huge force on standby in EU if required, let us hope it is not required.