Estonia, Latvia, and Lithuania: Background and U.S.-Baltic Relations [Updated January 2, 2020] [open pdf - 1MB]
From the Summary: "Estonia, Latvia, and Lithuania, often referred to as the Baltic states, are close U.S. allies and considered among the most pro-U.S. countries in Europe. Strong U.S. relations with these three states are rooted in history. The United States never recognized the Soviet Union's forcible incorporation of the Baltic states in 1940, and it applauded the restoration of their independence in 1991. These policies were backed by Congress on a bipartisan basis. The United States supported the Baltic states' accession to NATO and the European Union (EU) in 2004. Especially since Russia's 2014 invasion of Ukraine, potential threats posed to the Baltic states by Russia have been a primary driver of increased U.S. and congressional interest in the region. Congressional interest in the Baltic states has focused largely on defense cooperation and security assistance for the purposes of deterring potential Russian aggression and countering hybrid threats, such as disinformation campaigns and cyberattacks. Energy security is another main area of U.S. and congressional interest in the Baltic region."
CRS Report for Congress, R46139
Congressional Research Service: https://crsreports.congress.gov/