WASHINGTON (AP) — The military's top priority is to defeat al-Qaida and other extremists, but winning the wars in Iraq and Afghanistan alone will not achieve that, Defense Secretary Robert Gates says in a new defense policy document.

Nor will the use of force alone accomplish the mission, says the 2008 National Defense Strategy approved by Gates and released Thursday by the Pentagon. The most important thing the military can do, it said, is prepare friends and allied nations to defend and govern themselves.

"For the foreseeable future, winning the 'Long War' against violent extremist movements will be the central objective of the U.S.," the strategy paper said, adding that Iraq and Afghanistan "remain the central fronts in the struggle."

But, it added that the U.S. "cannot lose sight of the implications of fighting a long-term, episodic, multifront and multidimensional conflict more complex and diverse than the Cold War confrontation with communism."

The 23-page document asserted: "Success in Iraq and Afghanistan is crucial to winning this conflict, but it alone will not bring victory."

It also said the use of force plays a role but may be less important than "measures to promote local participation in government and economic programs to spur development, as well as efforts to understand and address the grievances that often lie at the heart of insurgencies."

Gates later told a Pentagon news conference that the military must maintain a balance to make sure it has the ability to win long-running irregular conflicts as well as keep up its conventional superiority.

"If I could describe the new national defense strategy in one word it would be 'balance,"' he said.