Complex sentence: The federal government promised the industrialists of Sialkot an international airport but due to bureaucratic red-tape, indifference by the government and more importantly its proximity to Indian administered Kashmir and the periodic shelling from across the border, no work could be started.
Split into simpler sentences: The federal government promised the industrialists of Sialkot an international airport. Due to bureaucratic red-tape, indifference by the government and, more importantly, its proximity to Indian-administered Kashmir and periodic shelling from across the border, no work could be started.