Sumner Welles, U.S. Under Secretary of State, issued a declaration that the U.S. government would not recognize the Soviet Union's annexation of the Baltic states.

Benjamin Sumner Welles was an American government official and diplomat. He was a major foreign policy adviser to President Franklin D. Roosevelt and served as Under Secretary of State from 1936 to 1943, during Roosevelt's presidency.

Under Secretary of State (U/S) is a title used by senior officials of the United States Department of State who rank above the assistant secretaries and below the deputy secretary.

The Welles Declaration was a diplomatic statement issued on July 23, 1940, by Sumner Welles, the acting US Secretary of State, condemning the June 1940 occupation by the Soviet army of the three Baltic countries – Estonia, Latvia, and Lithuania – and refusing to diplomatically recognize their subsequent annexation into the Soviet Union. It was an application of the 1932 Stimson Doctrine of nonrecognition of international territorial changes that were executed by force and was consistent with US President Franklin Roosevelt's attitude towards violent territorial expansion.

Diplomatic recognition in international law is a unilateral declarative political act of a state that acknowledges an act or status of another state or government in control of a state. Recognition can be accorded either on a de facto or de jure basis. Partial recognition can occur if many sovereign states refuse to recognize an entity as a peer. Recognition can be a declaration to that effect by the recognizing government or may be implied from an act of recognition, such as entering into a treaty with the other state or making a state visit. Recognition may, but need not, have domestic and international legal consequences. If sufficient countries recognize a particular entity as a state, that state may have a right to membership in international organizations, while treaties may require all existing member countries unanimously agreeing to the admission of a new member.