What countries in Western Europe collectively could stop Russia without the United States? And using what exactly? Their economy? What weapons? These countries are shells of themselves from the military power they once had. Russia has more land and natural resources, a huge nuclear arsenal, better Navy to include a new class of quiet nuclear powered submarines to severely limit the effectiveness of missile defense systems, tons of ground support, and are very proficient in running military drills. Again, I don’t think Putin would is going to attack a NATO country but in reality I don’t see how he could be stopped unless the USA is the one stopping him.