Huge Manhunt for Missing GI As Mystery Surrounds His Whereabouts

Senior U.S. military and diplomatic officials believe that more than three weeks after his capture by Afghan Taliban forces, Pfc. Bowe R. Bergdahl still remains in Afghanistan -- but acknowledge that he could have crossed the border into Pakistan.

"We think we would know if he's crossed the border," said a senior diplomatic official in South Asia, "but we just can't be sure."

Officials involved in the search for Bergdahl told ABC News Monday they were concerned his captors may have taken him into Pakistan.

The U.S. has flooded the area between Bergdahl's small base in Paktika province and the Pakistan border – roughly 60 miles – with "one of the largest operations we have in Afghanistan right now," according to U.S. Army spokeswoman Lt. Cmdr. Christine Sidenstricker. Those air and ground assets, U.S. officials believe, should be enough to prevent militants from taking Bergdahl across the border into Pakistan, where U.S. troops cannot officially operate, or at least enough to know if Bergdahl had been taken across the border.

But residents say the area is extremely difficult to navigate and local militants could easily hide and transport the soldier at will.

One South Waziristan resident who provides information to Pakistani intelligence services tells ABC News that Bergdahl, who left his base on June 30, was in South Waziristan earlier this month under the control of Taliban commander Mulvi Nazir. The resident was offered an opportunity to "interview" Bergdahl, but declined. Bergdahl was then transferred to North Waziristan, according to the same source, to the control of another Taliban commander, Hafiz Gul Bahadur.

Taliban Commanders

The senior U.S. official said the U.S. believed Bergdahl was still under the control of a different commander: the Afghan Mullah Sangeen, who Pakistani analysts believe is closely allied with the Afghan commanders Jalaluddin and Sirajuddin Haqqani. The elder Jalaluddin Haqqani, one of the U.S.' most prized assets during the mujahedeen's war against the Soviets, is now, with his son Siraj, the most dangerous commander in eastern Afghanistan, and held New York Times reporter David Rohde for months from a safe haven in North Waziristan.

But the South Waziristan resident said Sangeen's affiliation with Haqqani was overblown.

Sangeen was once very close to Haqqani, the resident said, but was now closer to Baitullah Mehsud, the head of the Taliban in Pakistan who operates out of South Waziristan. Sangeen was with Mehsud at a funeral attacked by a CIA drone missile one month ago. The missile just missed Mehsud, a local resident and a regional intelligence official told ABC News at the time.

If Sangeen is indeed close with Mehsud, then he could also be working with Nazir and Bahadur. Earlier this year Mehsud, Nazir, and Bahadur publicly declared they would work together to attack U.S. soldiers in Afghanistan. Haqqani was never part of that declaration.

Sangeen has publicly claimed responsibility for Bergdahl's capture, threatening to kill him if U.S. forces did not stop operations in two districts of Paktika province.

Sidenstricker declined to comment further on the search for Bergdahl other than to say, "we're using all available assets to return him safely to his unit and his family."

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