The United States today made it clear it cannot believe that slain terrorist Osama bin Laden had no support system in Pakistan. Deputy National Security Advisor for Counter-terrorism and Homeland Security John Brennan told reporters in Washington that it is 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. He also, hinted at probing any official links, while several top lawmakers accused Islamabad of playing a double-game. Brennan's remarks came a day after Bin Laden was shot dead yesterday by US forces in a house just yards away from Pakistan's Military Academy in Abbottabad near Islamabad. This has raised questions whether the establishment had knowingly harboured him. Brennan said, the US is going to pursue all leads to find out exactly what type of support system and benefactors that bin Laden might have had. He said, following the successful operation, a number of senior US officials are in regular contact now with their Pakistani counterparts.