The US has targeted North Waziristan and other areas on the Pakistan side of the border with drone-launched missile strikes, killing substantial numbers of militants as well as Pakistani civilians. The Pakistani army has undertaken an offensive against Taliban militants in South Waziristan but it has not expanded the effort into North Waziristan.
Obama administration officials have often asserted, as did the Bush administration, that they believe bin Laden is being sheltered on the Pakistani side of the border, along with other senior al-Qaida leaders. But Jones broke new ground by saying publicly that the al-Qaida chief may at times have slipped back into Afghanistan.
Sen. John McCain, R-Ariz., made a somewhat similar, if less specific, remark Sunday about bin Laden's movements. He told NBC's "Meet the Press" that knowledgeable people have told him that bin Laden "moves back and forth."
Two Afghan provinces in the country's northeast held particular attraction for bin Laden in the 1990s: Kunar and Nuristan. The towering mountains there hid bin Laden training camps that date back to the Soviet occupation of Afghanistan in the 1980s. A longtime bin Laden ally, Gulbuddin Hekmatyar, holds sway in the area. US troops have targeted Hekmatyar's security chief, Kashmir Khan, in Kunar.
During his years in Afghanistan as a guest of the Taliban, bin Laden operated mainly in the southern region around Kandahar.
Gates said he does not blame a lack of Pakistani cooperation for the absence of intelligence on bin Laden.
"No, I think it's because if, as we suspect, he is in North Waziristan, it is an area that the Pakistani government has not had a presence in, in quite some time," Gates said, adding that although the Pakistani government has its own priorities, any pressure it brings on the Taliban is helpful because it is in league with al-Qaida.
During a visit to Pakistan in late October, Secretary of State Hillary Rodham Clinton caused a stir by chiding Pakistani officials for failing to press the hunt for al-Qaida inside their borders. She said she found it "hard to believe" that no one in Islamabad knows where the al-Qaida leaders are hiding and couldn't get them "if they really wanted to."
Gates said he could not confirm recent news reports that bin Laden had been seen in Afghanistan earlier this year. BBC News reported last week that a Taliban detainee in Pakistan claimed to have met in January or February with an unidentified associate who said he had seen bin Laden just days earlier in Afghanistan, possibly in Ghazni province.