Speaking at the Global Counterterrorism Forum in Istanbul, Turkey, Clinton said 120,000 suspected terrorists have been arrested worldwide and more than 35,000 have been convicted in the past decade.
Clinton noted Osama bin Laden is dead and said al-Qaida's "core leadership ranks have been devastated," while many of the terrorist group's affiliates have lost key operatives.
"But despite this progress, the danger from terrorism remains urgent and undeniable," Clinton said. "The core of al-Qaida that carried out the 9/11 attacks and other attacks in countries represented here today may be on the path to defeat, but the threat has spread, becoming more geographically diverse as groups associated with al-Qaida expand their operations."
Clinton noted terrorists hold territory in Somalia, Yemen and Mali, and frequently carry out attacks in Nigeria and the Maghreb. In Turkey, she pointed out, tens of thousands of people have been killed in the Kurdistan Workers' Party campaign of terrorism and violence.
Clinton called for a broad, comprehensive, global approach to fighting terrorism.
"Just as the threat we face crosses borders and oceans, so must our response," Clinton said. "We need a strategic, comprehensive approach to counterterrorism that integrates both military and civilian power that uses intelligence, law enforcement, diplomacy, development, humanitarian assistance and every possible partner and asset because we have learned that to defeat a terrorist network, we need to do more than remove terrorists from the battlefield.
"We need to attack finances, recruitment and safe havens."
Clinton said leaders need to diminish the appeal of terrorism, particularly to young people, and improve conditions for women -- which she called a "bellwether for societies' security."
The forum, established in New York in September, is co-chaired by the United States and Turkey and has 30 members -- 29 countries and the European Union.