== == I don't think there can be a 100% guaranteed accurate answer, as the symbol which we know as the Nazi swastika has been around for hundreds, possibly a thousand years.
It appears that this seemingly universal symbol has had multiple origins at widely dispersed [both locale and time-wise], non-related locations around the world. I do not recall whether, or not, the swastika was a pre-Nazi historical symbol of Germanic history, or was newly adopted by the Nazi regiem from existing world-wide graphic symbols. I will continue to monitor this question in the hope that someone with specific knowledge will provide a more definitive answer. True. The symbol was used by the American Indians. During World War 1, one of the American squadrons had an Indian head for its aircraft markings, which had a small swastika on the headress. Prior to World War 2, the shoulder patch insignia for US 45th Infantry Division was a RED diamond(or square rotated 90 degrees) with a YELLOW swastika. After US declared war on Germany, the swastika was replaced with an Indian THUNDERBIRD. Archaeological evidence of swastika-shaped ornaments dates from the Neolithic period. An ancient symbol, it occurs mainly in the cultures that are in modern day India and the surrounding area, sometimes as a geometrical motif (as in the Roman Republic and Empire) and sometimes as a religious symbol. It was long widely used in major world religions such as Hinduism, Buddhism and Jainism.
Addendum: The the essential shape/symbol we know as the swastika is actually prehistoric & known/used by cultures all over the world. It is thought by some that it may have been inspired by the rotating sparks that flew from the fire-drill tool used by primitive Man to start campfires. Its historically ancient metaphysical symbol/symbolic sense included representing the alchemical Four Forces (Earth, Air, Fire, Water) rotating from East to West in creating & maintaining the World. Whatever, the word comes from the Sanskrit svastika, which basically means "well-being" (as understood so by the sages & mystics of ancient India). Until Hitler & the Nazis co-opted it as their emblem, it was believed & seen as a good luck symbol; and it's sad that it will never be seen again as anything but a symbol of evil because of their perverted use. It is well known that many of the high-ranking Nazis were into a lot of pseudo-mystical ideas & beliefs & so probable they adopted it as their "magic" symbol for good luck; however, they twisted the symbol to affect turning counter, as they believed they were going to reverse the Order & establish a new one. Fortunately, the Cosmic Order will not tolerate being messed with so, regardless of reasons, methods or beliefs. I'ts just sad - and amazing - that as the supposed most inteligent species on this planet we are so tragically slow to learn this...