Taliban and al-Qaeda have established their safe haven in western Pakistan, an influential Democrat Senator has said it is crucial to dismantle and neutralise these hot spots for the security of the US and other parts of the world. Following the successful US offensive in Afghanistan in 2001 and 2002, Taliban and al-Qaeda elements successfully relocated to western Pakistan. From there, they have created a sanctuary to attack US troops to destabilize eastern and southern Afghanistan, and to launch attacks on Pakistani military units and civilian installations, Senator Tom Casey said on the floor of the Senate. Casey, the Chairman of the Senate Foreign Relations Subcommittee responsible for the Middle east and South Asia, also expressed concern at the speed with which Taliban is gaining ground in Pakistan, especially in the areas close to Islamabad. "I know the administration is working with our partners in Pakistan to prevent the situation from deteriorating even further. We must continue to work with the Government of Pakistan to prevent these radical groups from destabilising the Pakistani State and the region," Casey said. Pakistan has a nuclear arsenal which would pose a grave threat should it fall under the control of extremists, he said. Recent gains of Taliban show how interrelated the threats in Pakistan and Afghanistan are, Casey said, adding the threat in Afghanistan feeds off the threat in Pakistan and vice versa. "We must treat this for what it is: one theater that requires a unified approach," he said. Supporting Obama's Af-Pak policy, Casey said an effective Congressional oversight is essential if the US is to have unity of purpose and unity of will to "disrupt, dismantle and defeat" al-Qaeda in Pakistan and Afghanistan and to prevent their return to either country in the future.