Usually the problem that the newspaper experts are refering is the size of the bomb. Making a nuclear bomb that is cumbersome and big is very easy, just put so

Usually the problem that the newspaper experts are refering is the size of the bomb. Making a nuclear bomb that is cumbersome and big is very easy, just put some plutonium there, and craploads of explosives (ie: "Fat Man" design). The problem is making a bomb that works, and is small and light enough to fit a long range missile warhead. shorter range missiles can be bigger (thus why you can put it more easily on them).