The Pentagons top military officer said Thursday hes concerned that the US troop buildup to roust insurgents from Afghanistan could further destabilise neighbouring Pakistan. However, Joint Chiefs of Staff Chairman Adm Mike Mullen, speaking to the Senate Foreign Relations Committee, said the military planning is under way to try to avoid that. Mullen said he believes the upcoming increase of 21,000 US forces in Afghanistan is about right for the new strategy of trying to quell the insurgency and speed up training of Afghan security forces. He was responding to Sen Russ Feingold, D-Wis, who said hes concerned the buildup may push militants into already troubled Pakistani regions and end up further destabilising Pakistan without providing substantial lasting improvement in Afghanistan. I share your concern, Mullen said. Your point about insurgents going particularly into Balochistan, but particularly across that border ... we all share the concern for that, Mullen said. Where Im comfortable is at least planning for it and having some expectation will allow us to address that, Mullen said. Officials are working to avoid it, and he thinks they can, Mullen said, adding, Pakistan is further away from being totally destabilised than a lot of people realize. Besides that, Mullen said he didnt know of any other way to provide for the security needed in Afghanistan outside of sending more troops. Pakistani military chief Gen Ashfaq Kayani has told US officials hes worried not only about Taliban moving across the border, but also the possibility that US forces could prompt an exodus of refugees from southern Afghanistan. Marine Commandant Gen James T Conway, whose troops are going into the south of Afghanistan, told a Pentagon press conference last month of Kayanis concern but said no one knows for sure where insurgents will move as US operations ramp up. There are others that think they may go in different directions, Conway said. But in any event, weve got to do what weve got to do in the south. And there will be pond rings coming off of that that I think were going to have to adjust to. Mullen said Pakistan was unlikely to lose focus on India, even as it had begun to realise the serious threat posed by the terrorists within the country. Its my view they are not going to lose their focus on India, Mullen said. Mullens remarks came in response to a question from Congressman Norman Dicks who wanted to know from him about the progress made by the US efforts in this regard, during a hearing of the Defence Subcommittee of the House Appropriations Committee. Theres been a lot of discussion about trying to get the Pakistanis to focus more on the insurgents and the Taliban and less on their concerns about India. Are we making any progress in that direction? he asked, to which Mullen responded that they (Pakistan) still consider a threat. Mullen said, Theyve got a challenge of literally two fights, a conventional fight or a conventional challenge and threat along with a counter insurgency challenge which they increasingly recognise. It is just going to take some time and our patience level with them is key to establish the long term relationship with them to one counter this threat, and two to have a relationship with them in that part of the world, which I think is absolutely critical, he added.