Complex sentence: Pakistanis "poured into the streets to protest the American assault," including 300 people in Islamabad, where protesters burned a U.S. flag outside the U.S. Information Service center.
Split into simpler sentences: Pakistanis "poured into the streets to protest the American assault," including 300 people in Islamabad. Protesters in Islamabad burned a U.S. flag outside the U.S. Information Service center.