For the United States and its allies, ending the al-Qaida threat calls for a modified military footprint, close work with partners and continued U.S. involvement in regions of the world where violent extremism has flourished, Defense Secretary Leon E. Panetta said tonight.

Addressing a large audience here at the Center for a New American Security, the secretary discussed significant national security challenges and opportunities ahead.

He also outlined priorities that characterize the approaching end of the longest period of sustained armed conflict in the nation’s history.

The priorities, Panetta said, are fighting the war against al-Qaida and its affiliates, ending the war in Afghanistan, implementing the new defense strategy, meeting fiscal responsibilities, countering nuclear proliferation, improving cybersecurity, achieving greater energy security, implementing the Asia-Pacific rebalance, and taking care of service members, veterans and military families.

“But tonight I wanted to focus on the goal that still remains at the top of the priority list, as it must. That goal that the president made very clear -- that we have a responsibility to disrupt, degrade, dismantle and ultimately defeat those who attacked America on 9/11 -- al-Qaida,” the secretary said.

“ … To protect Americans at home and overseas,” he added, “we need to continue to pursue al-Qaida wherever they go, whatever form they take, wherever they seek to hide. We must be constantly vigilant, we must be constantly determined to pursue this enemy.”

What will it take, he asked, to achieve the end of al-Qaida?

The essential first step is to finish the job that the United States and its coalition partners began in Afghanistan, he said, “and we are on track to do that.”

As the United States and its NATO partners agreed at the 2010 summit in Lisbon, Panetta said, Afghans must be responsible for their own security by the end of 2014.

This transition will require continued commitment by the international community and the United States to help Afghan forces achieve this goal, he added.

“We have come too far. We have invested too much blood and treasure not to finish the job,” the secretary said. “There are no shortcuts, nor can we afford to turn away from this effort when we are so close to achieving success and preventing al-Qaida from ever returning to this historic epicenter for violent extremism.”

In Afghanistan and Pakistan, prolonged military and intelligence operations have significantly weakened al-Qaida, Panetta said.

The terrorist group’s most effective leaders are gone, its command and control has been degraded and its safe haven is shrinking, he added, but al-Qaida remains.

“We have slowed the primary cancer but we know that the cancer has also metastasized to other parts of the global body,” the secretary said. Two examples of that spreading al-Qaida presence are Yemen and Somalia.

In Yemen, for example, the capabilities of al-Qaida in the Arabian Peninsula, or AQAP, are growing. This group has targeted the United States for attack and sowed violence and chaos in Yemen itself, Panetta said.

“We have struck back in an effort to disrupt and dismantle this group through a very close partnership with the government of Yemen … and the Yemenese themselves,” he added.

In Somalia, against the militant group al-Shaabab, progress also has been made, the secretary said, “in large part because of an effective partnership between the United States and the African Union Mission in Somalia.”

But the challenge is far from over, Panetta said.

“President [Barack] Obama has made clear, we will fight not just through military means but by harnessing every element of American power -- military, intelligence, diplomatic, law enforcement, financial, economic and above all the power of our values as Americans,” the secretary said.

The second step in achieving the end of al-Qaida, Panetta said, involves maintaining pressure on al-Qaida in Pakistan, on AQAP in Yemen, and on al-Qaida-associated forces in Somalia.

That means degrading the terrorists’ senior leadership, dismantling their organizational capabilities, remaining vigilant to ensure the threat does not reconstitute, and working to build the capacity of U.S. partners, including Pakistan, to confront these shared threats, he added.

“Despite challenges in the bilateral relationship between the United States and Pakistan,” the secretary said, “one area in which our national interests continue to align is defeating the terrorists on Pakistan soil that threaten both of us. We remain committed to pursuing defense cooperation based on these shared interests.”

A third step is to prevent the emergence of new safe havens for al-Qaida elsewhere in the world that the group could use to attack the United States or its interests, he said.

“The last decade of war has shown that coordinated efforts to share intelligence, to conduct operations with partners, are critical to making sure that al-Qaida has no place to hide,” Panetta told the audience.

“We will expand these efforts, including through support and partnership with governments in transition in the Middle East and North Africa,” he added.

“This campaign against al-Qaida will largely take place outside declared combat zones, using a small-footprint approach that includes precision operations, partnered activities with foreign special operations forces, and capacity building so that partner countries can be more effective in combating terrorism on their own,” the secretary said.

DOD will work whenever possible with local partners, he added, supporting them with intelligence and resources they need to deter common threats.

In Mali for example, Panetta said, “we are working with our partners in Western Africa who are committed to countering the emerging threat to regional stability posed by AQIM.”

A fourth step needed to bring an end to al-Qaida involves investing in the future, he added, in new military and intelligence capabilities and security partnerships.

“Our new defense strategy makes clear -- the military must retain and even build new counterterrorism capabilities for the future,” Panetta said.

As the size of the military shrinks, for example, special operations will continue to ramp up, growing from 37,000 members on 9/11 to 64,000 today and 72,000 by 2017, the secretary noted.

“We are expanding our fleet of Predator and Reaper [unmanned aerial vehicles] over what we have today. These enhanced capabilities will enable us to be more flexible and agile against a threat that has grown more diffuse,” Panetta said.

“We are also continuing to invest in building partner capacity, including through Section 1206 authority to train and equip foreign military forces. Our new Global Security Contingency Fund has been very helpful in placing new emphasis on cultivating regional expertise in the ranks,” the secretary added.

A final point that too often takes a backseat to operations against al-Qaida, Panetta said, is how to prevent extremist ideologies from attracting new recruits.

“Over the past decade we have successfully directed our military and intelligence capabilities at fighting terrorism,” he added. “And yet we are still struggling to develop an effective approach to address the factors that attract young men and women to extreme ideologies, and to ensure that governments and societies have the capacity and the will to counter and reject violent extremism.”

To truly end the threat from al-Qaida, the secretary said, “military force aimed at killing our enemy alone will never be enough. The United States must stay involved and invested through diplomacy, through development, through education, through trade in those regions of the world where violent extremism has flourished.”

This means continued engagement in Pakistan, he added, and following through on U.S. commitments to Afghanistan’s long-term stability.

Secretary of State Hillary Rodham Clinton has outlined a comprehensive strategy for North and West Africa that combines security assistance and economic development, strengthens democratic institutions and advances political reforms, Panetta said.

“ … We will be vigilant and we will posture our military and intelligence forces to prevent and if necessary respond to threats of violence against our interests throughout the Middle East and North Africa, including threats against our embassies and consulates, and our diplomats themselves,” the secretary said.

“But to truly protect America, we must sustain and in some areas deepen our engagement in the world –- our military, intelligence, diplomatic and development efforts are key to doing that,” he added.

Pursuing an isolationist path, the secretary said, “would make all of us less safe in the long-term.”

“This is not a time for retrenchment. This is not a time for isolation. It is a time for renewed engagement and partnership in the world,” Panetta said.