What are the exact threats russia has posed to the western interest?

During the Cold War, Russia and the West were at loggerheads with each other.  Both the Soviet Union and the United States of America armed themselves with nuclear weapons and were on high alert expecting the other to strike at any moment. After the fall of the Berlin War, the Soviet Union broke up into individual countries each with its own governments. The West believed that the Cold War was over. No one expected Russia to start invading the countries surrounding her. A good example of this is the Ukraine. Russia invaded the Crimea and declared it part of Russia. There is currently a civil war going on in Eastern Ukraine and Russian troops are involved. Experts believe that Russia might be expanding and conquering countries that were part of the Soviet Union.