Complex sentence: The islands signed a Compact of Free Association with the US in 1986 and up to 1999 the islanders received US $180M for continued American use of Kwajalein atoll, US $250M in compensation for nuclear testing, and $600m in other payments under the compact.
Split into simpler sentences: The islands signed a Compact of Free Association with the US in 1986. Until 1999 the islanders received US $180M for continued American use of Kwajalein atoll, US $250M in compensation for nuclear testing, and US $600M in other payments under the compact.