There have been more wars prior to tne 20th century which could be classified as being world wars, such as the Napoleonic Wars, Ghengis Khan are just a couple which come to mind. What has been happening in the Middle East over the past decade , and what is happening now, is not being referred to as a world war by anyone. The media is sold on giving the populus bread and circuses.
When this time is looked back on, it will be included in what is to come, the Great War.As more countries are drawn into the middle east conflict, there will eventually be a nuclear exchange in the middle east. Then things will go quiet. As the damage is surveyed and muslims stand together, the western nations will receive the blame.
Russia has become independent as a result of sanctions, and will be affected least of all.
The US will be recovering from economic difficulties when it is on the receiving end.
This great war will cause more destruction than either the 1st or 2nd world wars.