LONDON - US Secretary of State Hillary Clinton maintained Sunday that the siege of Pakistan Army Headquarters in Rawalpindi showed extremists were a growing threat to the nuclear-armed American ally, but she contended they did not pose a risk to the countrys atomic arsenal. Addressing a joint Press conference with British Foreign Secretary David Miliband after talks here, Hillary said there was nothing to suggest that Pakistans nuclear weapons could fall into terrorists hands despite Saturdays audacious Taliban attack on the GHQ that highlighted security weaknesses. She said extremists were increasingly threatening the authority of the state, but we see no evidence that they are going to take over the state. We have confidence in the Pakistani government and militarys control over nuclear weapons. Miliband said although Pakistan faced a 'mortal threat from extremists, there was no danger of its nuclear weapons being compromised. He scolded those who might raise the suggestion. I think its very important that alarmist talk is not allowed to gather pace, he said. Miliband said he and Hillary had spent much of their time discussing the conflict in Afghanistan, the situation in neighbouring Pakistan and the crisis over Irans nuclear programme. They deferred comment on the Obama Administrations review of how to handle Afghanistan, particularly following allegations of fraud in the presidential election in August. But they were firm on Iran, which is defying international demands to come clean about its nuclear ambitions. Before leaving London, Hillary met British Prime Minister Gordon Brown at Chequers, the prime ministers country retreat outside London, and stressed that the trans-Atlantic special relationship remained strong.