The US has expressed confidence in the safety of nuclear arsenals of India and Pakistan despite heightened tensions between the two neighbours in the wake of Mumbai terror attacks by a Pak-based terrorist outfit. "Obviously, these are two nuclear powers. Whenever you are dealing with terrorism in countries that are nuclear powers, it is always -- it creates a heightened concern. You know, obviously, the Pakistani government has enormous challenges...financially, politically, from terrorists," US Defence Department Spokesman Geoff Morrell said. "...we want to work with them and any others who find themselves in the situation, to make sure that their nuclear arsenals are always secure. We see no reason at this point to have any concern with regards to the security of either countries' arsenal. So I think that's sort of where we are at this point" he added. The senior Pentagon official would not get into the initial findings of the Mumbai attacks other than saying that there has been no direct request for US military assistance. " my knowledge there have been no direct requests for US military assistance in really any of the efforts in the wake of the tragic Mumbai attacks. It is clear, based upon the fact you saw the chairman travel to both India and Pakistan last week, that we take this problem very seriously and are in close coordination, discussion, consultation with the militaries in India and Pakistan" Morrell said. "I'm not going to get into what our level of discussions have been. I would suffice it to say that we are working closely with the Pakistani military, as we have before the Mumbai attacks. We are working closely with the Indian military, as we have as well for some time.