[1] A non-belligerent state differs from a neutral one in that it may support certain belligerents in a war but is not directly involved in military operations.
During World War II, Spain allowed and promoted the Spanish Blue Division of volunteers and conscripts to join the German forces on the condition that they would fight against the Soviet Union only and they would do it with German equipment and uniforms.
The aircraft were either scrapped due to poor condition or repaired and allocated in the Spanish Air Force if not reclaimed, or after a negotiated purchase.
[1] Although officially Ireland declared itself neutral in World War II, it can be disputed whether it was a non-belligerent or not,[2] as The Cranborne Report drew up by the Viscount Cranborne to the British War Cabinet noted regarding Irish-British collaboration.
While Sweden did not officially fight in the Winter War, a new Flying regiment was formed out of volunteers to aid Finland and took charge of defending Finnish Lapland; the aircraft for the regiment came directly from Swedish Air Force inventory.