The United States is asking Japan to shoulder about 20 billion yen over an eight-year period from fiscal 2012 for large-scale repair work at the US Marine Corps' Futenma Air Station in Okinawa Prefecture, bilateral relations sources said Thursday. But Japan has shown reluctance, saying it would give the impression that the base, whose planned relocation within Okinawa has been stalled by strong local opposition, may remain at its current location for the indefinite future, according to Japan's (Kyodo) News Agency. US officials have said that extensive repairs to the whole base, including the runway and hangars, are indispensible to ensure safety at the facilities given the aging of the base.