America won't shy away from using military force if necessary against terrorist groups such as al-Qaida, Secretary of State Hillary Rodham Clinton said Friday.

But the U.S. will also respect the rule of law, she said, including principles guiding the use of force in self-defense, respect for the sovereignty of other states, and the laws of armed conflict. Terrorism suspects will be detained humanely and "when we do strike," the U.S. will seek to protect innocent civilians, she said.

Clinton delivered her speech at John Jay College of Criminal Justice next to a rusted, twisted piece of the World Trade Center that will be mounted in the college's new classroom building. The college lost 68 alumni in the Sept. 11 attacks, most of them New York firefighters.

Her visit comes amid heightened security due to what officials were calling a credible but unconfirmed terror threat against New York and Washington, just before the 10th anniversary of the terrorist attacks. The United Nations is holding a conference on terrorism on Sept. 19.

Clinton cited an Associated Press investigation showing that at least 35,000 people have been convicted and 120,000 arrested worldwide on terrorism charges in the last decade.

"Al-Qaida leadership ranks have been devastated," she told the audience of students, professors and reporters. "Virtually every major affiliate has lost key operators."

Clinton said the current terrorist threat was made public in order to activate Americans into a "great network of unity and support" against those who would wreak violence on innocent people.

"It is a continuing reminder of the stakes in our struggle against extremism," she said.

Clinton also said terrorism suspects should be tried in civilian courts, as well as before military commissions when appropriate.

The United States "cannot afford to live in fear, sacrifice our values, or pull back from the world" over terrorism concerns, she said.