Countries have been continuously fighting over territories especially those who have oil deposits. They fight for the ownership of it even though it is very far away from them and won't let other country to take over them. Like, you already have resources in your country to begin with so, why do you still want to take other's territories? Just for the things that you can get from it? And after maximizing the things that you can get from it you will leave them afterwards? World War III is really possible if there are countries that will still be continuously greedy of other country's territories.
Perhaps it is all about the cost of extraction. In some countries, it cost as less as $2 per barrel to extract crude oil. But in countries such as the United States and Venezuela, the cost can be as high as $60 per barrel.