Complex sentence: At least one submarine is always armed and on active service, carrying 16 Trident II submarine-launched ballistic missiles each with a range of 7000 miles (11,000 km), and 12 independently controlled warheads each capable of destroying a large city.
Split into simpler sentences: At least one submarine is always armed and on active service, carrying up to 16 Trident II submarine-launched ballistic missiles. Each missile has a range of 7000 miles (11,000 km), and can carry 12 independently controlled warheads each capable of destroying a large city.