Possiblility only may be true :: 1)US arch rival is Russia which has strong bond with India ......so nuclear weaponisation India means they will lose control among the complete axis of asia and Africa .........once in 1980 during cold war they ask for possesion in Indian ocean for their nuclear submarine to attack sovit Union ..... but India denied 2) They also know how brilliant Indians are ........ one day if not controlled India can deter US too in Nuclear weapons ..... as you know UPA govt stopped the development of Surya ICBM which can reach any US target too .... just to impress west