Terrorism has been labeled an un-winnable war, but terrorists groups can be defeated, according to United States Defense Secretary Leon Panetta. He said Saturday the U.S. is close to taking down Al Qaeda as a terrorist threat, a war America has fought for a decade.

Speaking with reporters aboard a U.S. Air Force jet on his way to Afghanistan, Panetta said the U.S. is within reach of defeating Al Qaeda, and all that remains is killing or capturing the terrorist group's remaining 10 to 20 leaders.

U.S. President Barack Obama announced recently the plan to withdraw 30,000 American troops from Afghanistan over the course of the next year and a half, but Panetta's remarks are the most definitive to date that the war against Al Qaeda can be won.

If we can be successful at going after them, he said aboard the U.S. Air Force jet, I think we can really undermine their ability to do any kind of planning to be able to conduct any kinds of attack on this country. That's why I think (Al Qaeda's defeat is) within reach.

Panetta put no timeline on America's victory over Al Queda, saying only more work is required.

The U.S. landed a major victory in the spring when Al Qaeda leader Osama bin Laden was killed. Al Qaeda issued a statement at the time saying the death of the group's leader, at the hands of U.S. armed forces on the hunt for him for a decade in response to the deadly attacks on America orchestrated on September 11, 2001, was a curse that chases the Americans and their agents and goes after them inside and outside their countries.

Al Qaeda further warned in the statement, issued in May, that bin Laden's death at the hands of U.S. forces would not be wasted in vain.

But Panetta, a former California congressman who once headed the CIA before he was chosen by Obama to replace Robert Gates as Defense Secretary, said in June the U.S., in the moment following bin Laden's death, was further turning up its pressure on Al Qaeda to put maximum pressure on the organization because he believed that if we continue this effort we can really cripple Al Qaeda as a threat to this country.

Among the 10 to 20 Al Qaeda leaders remaining at large the U.S. needs to kill or capture is Ayman al Zawahiri, an Egyptian who succeeded bin Laden at Al Qaeda's top leader when bin Laden was killed. the U.S. thinks Ayman al Zawahiri is hiding in Pakistan's Federally Administered Tribal Areas, a remote region along the Afghanistan border. The U.S. wants Pakistan's help in finding Zawahiri.

Zawahiri is one of those (terrorist leaders at large) we would like to see the Pakistani's target along with our help, Panetta said.