Complex sentence: Wendy Sherman was the Clinton administration's policy coordinator for North Korea, which first arrived at the 1994 Agreed Framework under which, North Korea agreed to freeze and dismantle its nuclear weapons program, including its main reactor at Yongbyon.
Split into simpler sentences: Wendy Sherman was the Clinton administration's policy coordinator for North Korea. The Clinton Administration had first arrived at the 1994 Agreed Framework under which, North Korea agreed to freeze and dismantle its nuclear weapons program, including its main reactor at Yongbyon.