[tim333]

Switzerland has also had a policy of armed neutrality since 1815 or before I think and the armed bit would probably be a headache for anyone invading.

[lolc]

The Nazis did plan an invasion. See Operation Tannenbaum[0].

Switzerland didn't end up getting divided between Germany and Italy thanks to the Red Army hurtling more humans west than the Wehrmacht could supply bullets east. Swiss munitions production wouldn't be risked.

[0] https://en.wikipedia.org/wiki/Operation_Tannenbaum