Cartwright, briefing the media at the Pentagon on the Af-Pak annual review unveiled by President Barack Obama, acknowledged, "I see this sanctuary issue and then the extremist groups that are associated with it -- particularly those that come back across the border into Afghanistan -- as one of the strategic vulnerabilities."
Cartwright, who had earlier appeared with Obama, Defence Secretary Robert Gates and Secretary of State Hillary Clinton at the White House briefing room, said, "Now, there are any number of ways that we can address it -- from unilateral US activities to unilateral Pakistani activities inside Pakistan to partnering between the two of us, which is really what we seek."
Mullen, who made an unannounced visit to Pakistan en route from Iraq last week to meet with Pakistan's Chief of Army Staff General Ashfaq Pervez Kayani, just hours before the White House released its Af-Pak review, had expressed 'impatience' with Islamabad over its continuing failure to dismantle the terrorist havens within its borders.
He told reporters traveling with him on his special military aircraft that "these sanctuaries are a priority in military-to-military relationship between the US and Pakistan and our discussions."
"We have a sense of urgency about this operation as our forces are losing people on the other side," he said, and argued that Pakistani military action in North Waziristan is imperative because "that's where the Al Qaeda leadership resides -- that's where the Haqqani network is headquartered."
Cartwright said that the mobilisation of nearly 140,000 troops by Pakistan clearly indicated that "the Pakistanis have realised the threat inside their country."
While acknowledging that "this threat may not necessarily be the same threat that is focused on Afghanistan on all cases," nonetheless the US was gratified
that "we are seeing the ability to go after this threat in the coordination and cooperation," along the border where the US and Pakistan have joint centers.
Cartwright said this activity of joint monitoring and intelligence sharing "is moving faster in the last two months than it has in the preceding 18 months."
But he reiterated "The Pakistanis are clearly focused on the threats to their country first and then those that we are concerned about on the other side of the border," and consequently for all the coordination and cooperation, "I still count this as a strategic vulnerability (the continuing existence of terrorist safe havens within Pakistan)."
Michelle Flournoy, defence under secretary for policy, also acknowledged that there can be no success in Afghanistan unless these terrorist safe havens in Pakistan were dismantled.
Flournoy said, "Certainly as we degrade Al Qaeda's ability to operate from sanctuary and we increase the capability of both the Pakistani military and the American military, we create a situation where we will have more local and regional capacity to deal with this problem."
But she admitted, "Sanctuary is a strategic advantage for the Taliban, for Al Qaeda, for the syndicate of groups, and we do have to work together with the Pakistanis to diminish that over time."
Cartwright, when asked about reports that senior level officers in the Pakistani military and intelligence were assisting and funding the Afghan Taliban, said, "I don't have a factual basis on which to make that claim. I just don't know that."
When pressed on what back-up plan the US had if the Pakistanis don't dismantle the terrorist safe havens, Cartwright said, "The preferred method is for a partnered activity. It could be just the Pakistanis on their side of the border and the Afghanis and ISAF on the other side of the border."
Cartwright said, "It could be that we offer the training and the equipment and what not to help to make the activity as efficient as we can."
"The question of going further to unilateral action, that would be an absolute last measure because it has so many other impacts on the relationship -- that we really hate to end up in that position," he added.