WASHINGTON (Agencies) - US President Barack Obama has said that Pakistans large nuclear arsenal is a worry for the US especially at a time when terror outfits like Al-Qaeda and Taliban are trying to get such weapons. The Presidents comments coincided with the release of the latest satellite photos, which revealed that Pakistan is multiplying its nuclear arsenal. Obama also said it is 'absolutely imperative for the US to take the 'leadership in meeting the security challenges spawned by nuclear proliferation in the world 'particularly at a time when countries like North Korea and Iran are in the process of developing nuclear weapons capacity, at a time when we see a country like Pakistan with large nuclear arsenal on the other side of a long-running conflict in the Subcontinent with India, at a time when terrorist organisations like Al-Qaeda are trying to seek fissile material. Obama made the reference on potential threats after an Oval Office meeting with former secretaries of state George P Shultz and Henry Kissinger, former Defence Secretary William Perry and former Senator Sam Nunn of Georgia on Tuesday. We do not want a world of continued nuclear proliferation and that in order for us to meet the security challenges in the future America has to take the leadership in this area, he added. Meanwhile, US Secretary of State Hillary Clinton on Wednesday voiced confidence in the safety of Pakistan nuclear assets and said there is no reason to believe that the key regional ally battling the Taliban and Al-Qaeda along its Afghan border would divert the US economic assistance to advancing its nuclear programme. Testifying before the Senate Appropriations Committee on the State Departments $ 48.6 billion budget request for the financial year 2010, she saw an all-out effort by Islamabad to purge its northwestern areas of Taliban militants. The chief US diplomat told the lawmakers that the US is for the first time engaging with the South Asian nation in a comprehensive manner that would allow Pakistan face off economic and security challenges. I think there is no basis for believing that any of the money that we are providing will be diverted into nuclear programme, she stated when Senator Patrick Leahy, chairing the hearing, sought the administrations position on the subject. Assuring the Senators of the safety of Pakistans nuclear assets, Clinton ruled out an immediate extremist threat to them. Part of the reason why we are encouraged by the militarys strong response in Buner and Swat is because we do not want to see the Pakistani state threatened with the advance of the Taliban. We are assured by the Pakistan military and the government that they have control over their nuclear weapons at this time. And we have offered and continue to work with them in any way that they deem appropriate to help them assure the safety and security of those nuclear weapons. I do not see that as an immediate threat but it is certainly one that we take very seriously. In the strategic perspective, Clinton also underscored the need for Pakistan and India to build mutual confidence. Obviously we believe India and Pakistan can take more steps to build confidence between the two of them that would lessen the need for a nuclear deterrence in the eyes of the Pakistani or the Indians. Focusing on challenges in Afghanistan and Pakistan, she said, Washingtons efforts center on the Presidents (Barack Obamas) goal to dismantle, disrupt and defeat al-Qaeda. We know this requires a balanced approach and it takes more than military might alone. So we are expanding civilian effort and we are ensuring that our strategy is fully integrated and adequately resourced. We are supporting the Pakistani military as they take on the extremists that confront their countrys stability. We are making long-term investments in Pakistans people and the democratically elected government through targeted humanitarian assistance. She said the administration will hold itself and its two South Asian partners accountable toward defined objectives. We are seeking resources to deploy a new strategic communications strategy. We have to do a better job of getting the story of values, ideals, the results of democracy out to people, who are being fed a steady diet of the worst kind of information (by extremists). Clinton, who had last month expressed deep concern at Pakistan not moving against militants along its Afghan border, praised the Pakistani anti-militancy resolve in Swat. Monitoring Desk adds: Hillary Clinton admitted that Pakistan's present problems were due to American policy during 1980s. US policy on Pakistan was always like one step ahead and two steps back, she added, reported a private TV channel. She said Washington always encouraged Pakistani dictators by inviting them to official dinners. In the changing scenario, the US also gambled on General Musharraf, she added.