"I think it's inconceivable that bin Laden did not have a support system in the country that allowed him to remain there for an extended period of time," John Brennan, Deputy National Security Advisor for Counterterrorism and Homeland Security, told reporters at a crowded White House news conference here.
"I am not going to speculate about what type of support he might have had on an official basis inside of Pakistan."
Bin Laden was killed in a pre-dawn operation yesterday in Pakistan's Abbottabad. He was living in a three-storey house in the garrison town, barely two hour drive (120 km) from Islamabad .
"We are closely talking to the Pakistanis right now. And, again, we are leaving open opportunities to continue to pursue whatever leads might be out there," Brennan said responding to questions on how the most wanted terrorist was found in one of the most affluent neighborhoods of Islamabad, which is residences of top retired Pakistani military officials.
"People have been referring to this as hiding in plain sight. Clearly, this was something that was considered as a possibility. Pakistan is a large country. We are looking right now at how he was able to hold out there for so long and whether or not there was any type of support system within Pakistan that allowed him to stay there," Brennan said.
"We know that the people at the compound there were working on his behalf, and that''s how we ultimately found our way to the compound. But we are right now less than 24 hours after this operation, so we are talking with the Pakistanis on a regular basis now. And we''re going to pursue all leads to find out exactly what type of support system and benefactors that bin Laden might have had," he said.
Brennan said following the conclusion of the successful operation, a number of senior US officials are in regular contact now with their Pakistani counterparts. "We are continuing to engage with them. We''re engaging with them today as we learn more about the compound and whatever type of support system bin Laden had."
Brennan said the fact that bin Laden was found so close to the capital "raises questions".
"There are a lot of people within the Pakistani government, and I'm not going to speculate about who or if any of them had fore-knowledge about bin Laden being in Abbottabad. But certainly his location there outside of the capital raises questions. We are talking to the Pakistanis about this."
"But they, at least in our discussions with them, seem as surprised as we were initially that bin Laden was holding out in that area," he added.