Had no effect on the war I think because it was fought after the treaty was already signed.
Answer:
1. Japan: Allies
2. Russia: Central Powers
3. Scandinavia: Neutral Nations
4. Spain: Neutral Nations
5. Switzerland: Neutral Nations
6. Turkey: Central Powers
A war instigated by a major power that does not itself become involved. for example the cold war and their proxy wars which are Vietnam war, korean war, ect.