Because, we are told we must be prepared for war with Russia. Because Russia threatens American oil concessions in the Middle East.
Oil is fuel and, thus, a source of energy.
America is the greatest producer of oil, but also the greatest consumer. The day may come when America will import more oil than it exports. Especially in the event of hostilities, oil will be the decisive raw material, and American oil resources may not suffice to lubricate and fuel another war of several years' duration. Consequently, it is argued, we must prepare ourselves with atomic weapons for a war, even a preventive war. This is a chain of fallacious arguments.