Only some of the EU nations would back them. Germany and France are likely to stay neutral, along with other smaller nations such as Norway, Denmark, the Netherlands, Belgium, Spain, Portugal, Austria, Czechia, Slovakia, and Hungary. The only major EU nation which is going to side with the United States will be the United Kingdom (but this move will almost certainly trigger the secession of Scotland). In addition to the UK, the most rabid russophobe nations, such as Poland, Latvia, Lithuania, Romania, and Estonia are likely to side with the USA.