Per AI:
Yes, U.S. presidents have unilaterally withdrawn from treaties without congressional approval, establishing a precedent of unilateral presidential termination that became the norm in the 20th century.
This practice began in 1899 when the McKinley Administration terminated parts of a commercial treaty with Switzerland, and continued in 1927 when the Coolidge Administration withdrew from a convention with Mexico to prevent smuggling. During the Franklin Roosevelt Administration and World War II, such unilateral terminations increased significantly. A key legal case, Goldwater v. Carter (1979), involved President Jimmy Carter’s termination of the U.S. defense treaty with Taiwan without Senate or congressional approval. The Supreme Court dismissed the challenge, deeming it a political question outside judicial review, thus allowing the practice to stand.
Subsequent presidents have continued this precedent:
Donald Trump withdrew from the INF Treaty, Paris Climate Agreement, JCPOA (Iran nuclear deal), and the Open Skies Treaty without congressional consent.
Joe Biden unilaterally withdrew from a tax treaty with Hungary.
While Congress has occasionally passed laws to restrict such actions—such as the 2024 NDAA provision blocking NATO withdrawal without Senate approval—the executive branch maintains that the president has constitutional authority to terminate treaties unilaterally, provided it aligns with international law. This power, though contested, remains well-established in practice.