Yes. A number of European countries are neutral and were neutral during conflicts such as World War II. Ireland, Sweden and Switzerland are three such countries, and there are others.
It was neutral.
During the World War II period, the countries that most evidently threatened world peace were Germany and Japan. It was these two countries, in fact, that initiated the war by making unannounced attacks upon neutral countries and otherwise aggressively advancing their expansion to the detriment of their neighbors.
what was the percentage of bystanders who did what? percent is a measure of proportion, there needs to be another reference point. do you mean of the world's population? do you mean only of those involved in the Holocaust? but then you say World War II, so do you mean 'which countries were neutral in World War II?' the question is impossible to answer as it is.
Afghanistan was neutral during the war.
To avoid being invaded. Also, going to war was bad for the economy, the country's morale and pointless if they didn't stand to gain anything.
Sweden was neutral in Word War II.
Ireland chose to be neutral and stuck to that policy during World War II, and it is still a neutral country.
Germany invaded France during World War II.
Lots
Both world wars had Germany on one side and Britain, France, the United States, Russia, and China on the other. Differences include the fact that the Russia of World War I was the imperial Russian Empire while the Russia of World War II was the communist Soviet Union. Countries that changed sides include Turkey (for Germany in World War I, neutral in World War II), the Austro-Hungarian Empire (for Germany in World War I, no longer existed by the time of World War II), Italy (against Germany in World War I, for Germany in World War II), and Japan (against Germany in World War I, for Germany in World War II).
Preventive war is an attack made on another nation because of the possibility of it attacking you in the future. In World II both Axis and Allies attacked neutral countries for prevention.