Complex sentence: Over the next three years, the CIA attempted to subvert Sukarno by financing his political opponents, until 25 September 1957 when President Eisenhower ordered the CIA to overthrow the Sukarno government.
Split into simpler sentences: Over the next three years, the CIA attempted to subvert Sukarno by financing his political opponents. This happened until 25 September 1957 when President Eisenhower ordered the CIA to overthrow the Sukarno government.