In April 1898, while Congress prepared to authorize military force against Spain, some members were wary that the United States would annex Cuba rather than allow its independence. Senator Henry M. Teller of Colorado proposed an amendment disclaiming any intention to control Cuba. Congress passed the amended joint resolution on April 19; President William McKinley signed it on April 20.
Records of the U.S. House of Representatives, National Archives and Records Administration
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The United States hereby disclaims any disposition or intention to exercise sovereignty, jurisdiction, or control over said Island except for pacification thereof, and asserts its determination, when that is accomplished, to leave the government and control of the Island to its people.
Teller Amendment, April 16, 1898