Gen Stanley McChrystal, the top U.S. commander in Afghanistan told Congress Tuesday that killing or capturing bin Laden is critical to defeating al-Qaeda since he had become an "Iconic figure" among terrorists.

"I believe he is an iconic figure at this point whose survival emboldens al Qaida as a franchise organization across the world," McChrystal told the Senate Armed Services committee. "I don't think we can defeat him until he is captured or killed."

He said President Barack Obama's deployment of 30,000 extra troops in Afghanistan meant success was possible.

Military officials believe a Taliban-controlled Afghanistan will provide safe haven to al Qaida and its leadership. McChrystal estimated that between 24,000-27,000 full-time Taliban fighters operate in Afghanistan.

In the past, officials have said that killing bin Laden is not critical to defeating al Qaida, saying that they believe al Qaida's leadership is decentralized and that stabilizing the countries where they operate is a more attainable goal.

On Tuesday, however, McChrystal said that the goals are interlinked. "Rolling back the Taliban is a prerequisite to the ultimate defeat of al Qaida," he said.