From the Document: "United States European Command (or EUCOM, pronounced 'YEW-com') is headquartered in Stuttgart, Germany, and was established in 1952. Today its area of responsibility comprises 51 countries stretching from Portugal's Azores Islands to Iceland and Israel. USEUCOM's commander is currently U.S. Army General Curtis Scaparrotti, who is simultaneously NATO's Supreme Allied Commander, Europe (SACEUR). During the Cold War, the European theater was a primary focus for U.S. defense and national security and EUCOM was focused almost exclusively on deterring, and if necessary defeating, the Soviet Union. At the height of the Cold War, there were more than 400,000 U.S. troops stationed in Europe. [...] [...] Events in recent years, particularly since 2014, have tested, if not undermined, the strategic assumptions underpinning EUCOM's posture. To Europe's east, Russia annexed Crimea, began a proxy war in Eastern Ukraine, and is modernizing its conventional and nonconventional forces. Russia also increased its military activities in Europe's high north, particularly through reportedly adding nuclear-capable missiles to Kaliningrad (a Russian territory on the Baltic Sea that is not contiguous with Russia itself), enhancing its air patrolling activities close to other states' airspace, and enhancing its naval presence in the Baltic Sea, the Arctic Ocean, and the North Sea. Taken together, these moves have heightened some congressional concerns about Russian aggression and its implications for NATO territories, particularly among Central and Eastern European NATO allies."
CRS In Focus, IF11130
Congressional Research Service: https://crsreports.congress.gov/