WASHINGTON (Online) - Keeping up pressure on Pakistan to strike at militant groups in North Waziristan, US has warned if Islamabad does not become a part of the solution, it could be branded as part of the problem. Pointing out that militant groups were sheltering in the rugged area, the Under Secretary of Defence for Policy, Michele Flournoy said US is engaged in a very 'candid and intensive discussions with Pakistan about how they can together deal with some of these groups. 'Insurgency continues to benefit from sanctuaries and support inside Pakistan. This has contributed to rise of cross-border incidents and the security situation in Regional Command East remains tenuous as a result, Flournoy said. 'Safe havens along the border between Afghanistan and Pakistan are a very serious problem, and they are at the top of our agenda in our engagement with the Pak government, she said. Labelling the Tribal Areas along the border with Afghanistan as 'under governed regions, the top Pentagon official said, 'there are groups operating in these areas that do very much pose a threat, not only to our campaign in Afghanistan and Afghans future stability, but also I would argue to the future stability and viability of Pakistan itself. She said it was in Pakistans interest to have a friendly, stable, and secure Afghanistan on its border. 'But thats not something theyve experienced historically for a very long time. So we have a lot of work to do to convince them that outcome as possible and that its something that they should be part of achieving, she said. The Pentagon official said it was unacceptable to US to have pockets along the border where militants come across and attack Afghans, attack US interests, the Embassy for example, attack our soldiers. 'We want to do this in cooperation with Pakistan that this has become a serious force protection issue for us, and we will pursue means necessary to deal with this problem, Flournoy said. The Pentagon official said even though the US has several billions of dollars of security assistance in the pipeline, very little of that is being delivered to Pakistan now because most of its equipment deliveries require training. 'Well, Pakistan, in the wake of the Osama bin Laden raid and other things, asked us to pull all our trainers back. So we cant impart training on the equipment. So we cant deliver the equipment. So this is blocking the delivery of a lot of assistance thats already in the pipeline, she said. The US official also said that some financial payments owed to the Pakistani government had not been released for the last two quarters because we need to see concrete progress on some of our counter-terrorism objectives together. 'I believe that we can be successful in Afghanistan even with some degree of continued safe havens in Pakistan, but it will be much more difficult and much more resource intensive to sustain that success, she added. But, the Pentagon official declared that Washington would continue to degrade the insurgency and put pressure on safe havens in Pakistan in a way that will reduce that threat, she said.