That is the hakaristi or hakenkreuze (hooked cross), and its been a Finnish military symbol since the beginning of the 20th century.
It is a traditional heraldic device in England, Russia, most of the Nordic states, Poland, Holland and Spain. It even crops up in ancient Trojan and Mesopotamian dig sites now and again. It is universally used in Japan to mark places of religious or spiritual importance. You see it on temples, maps and shrines all over Japan, particularly the Buddhist ones.
The swastika is a religious symbol used frequently in Hinduism and Buddhism and is also found in indigenous North American symbology. In Indonesia it is the symbol for 'all power', taken from animist beliefs of a single non-corporeal creator. It is actually a traditional symbol in a lot of Asian nations, China and Korea being chief among them.
Just because it was used by one regieme as their national symbol for 12 years, doesn't mean that we should recoil in horror every time we see it. To millions upon millions of people it has nothing to do with war, nazism or racism, and is actually a symbol of peace or religious devotion.