Complex sentence: He withdrew the United States from participation in the 1998 Kyoto Protocol on world climate change and from the 1972 Anti-Ballistic Missile Treaty, as well as withdrawing U.S. support for the International Criminal Court, but his legacy was defined by his response to the 9/11 atrocities.
Split into simpler sentences: He withdrew the United States from participation in the 1998 Kyoto Protocol on world climate change and from the 1972 Anti-Ballistic Missile Treaty, as well as withdrawing U.S. support for the International Criminal Court. But his legacy was defined by his response to the 9/11 atrocities.