South Sudan, one of the world's least developed countries, aims to lay a fibre-optic network this year to link the capital Juba with submarine cables in east Africa to cut the high cost of using the Internet, a senior official said on Tuesday.South Sudan, one of the world's least developed countries, aims to lay a fibre-optic network this year to link the capital Juba with submarine cables in east Africa to cut the high cost of using the Internet, a senior official said on Tuesday.