U.S. Defense Secretary Robert Gates says it has been "years" since the United States had good intelligence on the whereabouts of Osama bin Laden.
In interviews broadcast Sunday on U.S. news programs, Gates and Secretary of State Hillary Clinton emphasized the importance of killing or capturing the al Qaida leader.
While U.S. military officials have long believed that bin Laden is hiding in Pakistan's tribal areas, Pakistani officials insist he is not in their country. Despite the disagreement, Clinton said Pakistanis have experienced a significant change in attitudes regarding terrorism and now see militant groups as a growing threat to their nation.
Both U.S. officials Sunday also defended President Barack Obama's decision to first send 30,000 additional troops to Afghanistan before beginning to withdraw forces in about 18 months.
They said that deadline is not firm, but will be based on conditions in Afghanistan.
They also said the president's July 2011 withdrawal date sends a message to the Afghan government about the importance of quickly building-up its security forces.
Afghan and U.S. officials are emphasizing the importance of holding peace talks with Taliban factions willing to give up violence and join the political process.
Clinton says she is "highly skeptical" that any of the current Taliban leaders would be ready to accept such conditions before holding talks. Gates said prospects for talks will improve if U.S. and Afghan forces can halt the insurgents' momentum on the battlefield.
The international force in Afghanistan says it carried out an air strike early Sunday in Laghman province, killing a group of militants. The force also says a U.S. soldier was killed by a bomb in eastern Afghanistan Saturday.
U.S. Marines launched an operation Friday in the Now Zad valley of Helmand province to try to disrupt Taliban supply lines. The operation involves about 1,000 Marines, 150 Afghan troops and an unspecified number of British soldiers.
Now Zad was once the second biggest town in Helmand, but is now nearly empty, after residents fled violence. Taliban forces have been using the area to transport drugs, weapons and fighters.
Some information for this report was provided by AFP and Reuters.