Couldn't be easier, between all of the decal sets out there for aircraft.
This question or one like it comes up on the forum quite a bit. The best way to understand it is to read the wikipedia page on the swastika.
Germany and Austria ban it's display, except in scholarly publication. Poland and Hungary have similar laws, as does Lithuania which also outlaws Soviet symbols. They define it as a symbol of organized crime, after it's adoption and usage by Nazi Germany, and prosecute under law similar to our own RICO statutes.
That makes the importation and sale of models into those countries, that include the swastika on the box art, in the instructions or decals, illegal. If you buy used kits on eBay, it's not uncommon to find stuff cut out of the decals, marked out on the box because the model may have spent some time in a LHS in Germany. A number of kits come with the thing in pieces, to be assembled on the model.
It's unwise to tell others how to legislate themselves, but given the havoc caused by organizations that did, and still do, use it, probably nuff said. It's also really simple to work around.
Thats a summary of the situation, but read wiki. It's a really interesting symbol with a lot of history.