"The core of al-Qaeda that carried out the 9/11 attacks may be on the path to defeat, but the threat has spread, becoming more geographically diverse," Clinton said ahead of a counter-terrorism meeting.
"We will always maintain our right to use force against groups such as al-Qaeda that have attacked us and still threaten us with imminent attack."
Although the group has lost serious blood after its core leadership ranks were destroyed, Clinton said, "the danger from terrorism remains urgent and undeniable."
She was referring to the recent killing of al-Qaeda number two Abu Yahya al-Libi Tuesday, after a US drone strike dealt the most weighty blow to the group since the killing of its mastermind, Osama bin Laden.
Since US President Barack Obama took office in 2009, US forces have been engaged in a relentless attempt to crush the group in various countries Afghanistan, Pakistan and Yemen.