Complex sentence: Bush favors building a new U.S. base in Anbar province, and believes American ground troops would not be needed to defeat the Islamic State group, But he has not commented on adding to the approximately 3,500 U.S. troops in Iraq now.
Split into simpler sentences: Bush favors building a new U.S. base in Anbar province, and believes American ground troops would not be needed to defeat the Islamic State group. But, he has not ruled adding to the approximately 3,500 U.S. troops in Iraq now.