WASHINGTON (AFP) - US intelligence has shown Iran could launch an attack against Europe with scores or hundreds of missiles, prompting major changes to US missile defences, Pentagon chief Robert Gates said on Thursday. President Barack Obama in September cited a mounting danger from Irans arsenal of short and medium-range missiles when he announced an overhaul of US missile defence plans. The new programme, called the phased adaptive approach, uses sea and land-based interceptors to protect Nato allies in the region, instead of mainly larger weapons designed to counter long-range missiles. One of the elements of the intelligence that contributed to the decision on the phased adaptive array was the realisation that if Iran were actually to launch a missile attack on Europe, it wouldnt be just one or two missiles or a handful, Gates told a senate hearing. It would more likely be a salvo kind of attack, where you would be dealing potentially with scores or even hundreds of missiles. Top US generals have said the new anti-missile system was meant to guard against a potential salvo of missiles from states such as Iran or North Korea. Gates made the comment when asked by Republican Senator Saxby Chambliss if he supported deploying improved missile defences, including plans for an upgraded SM-3 missile by 2020, even if Russia objected. Gates said he backed the 10-year plan, despite possible resistance from Moscow, saying the new missile defences would give us the ability to protect our troops, our bases, our facilities and our allies in Europe. Gates, along with other top deputies in the Obama administration, appeared before the Senate Armed Services Committee to argue for ratification of a new nuclear arms control treaty with Russia, trying to reassure Republican lawmakers the agreement posed no threat to the missile defence programme.