Complex sentence: The AFL-CIO's support enraged the Communist regimes of Eastern Europe and the Soviet Union, and worried the Carter Administration, whose Secretary of State Edmund Muskie told Kirkland that the AFL-CIO's continued support of solidarity could trigger a Soviet invasion of Poland.
Split into simpler sentences: The AFL-CIO's support enraged the Communist regimes of Eastern Europe and the Soviet Union. Its support worried the Carter Administration, whose Secretary of State Edmund Muskie told Kirkland that the AFL-CIO's continued support of solidarity could trigger a Soviet invasion of Poland.