A non-belligerent is a person, a state, or other organization that does not fight in a given conflict. The term is often used to describe a country that does not take part militarily in a war. The status does not exist in international law.
A non-belligerent state differs from a neutral one in that it may support certain belligerenta in a war but is not directly involved in military operations. The term may also be used to describe a person not involved in combat or aggression, especially if combat or aggression is likely. In a situation of civil unrest such as a riot, civilians may be divided into belligerents, those actually fighting or intending to fight, and non-belligerents who are merely bystanders.
United States of America
A notable example of non-belligerent in an environment of total war was the United States economic support of the Allies in World War II, prior to their entry into the war following the Japanese attack on Pearl Harbor. The economic support given by the Americans was through the Lend-Lease Program in which the United States provide the United Kingdom "all possible assistance short of war" in the words of Winston Churchill, but they remained a non-belligerent state in the war until Congress formally declared war on Japan following the attacks on Pearl Harbor.
Although officially Ireland declared itself neutral, it can be disputed whether it was a non-belligerent or not, as The Cranborne Report drew up by the Viscount Cranborne to the British War Cabinet noted regarding Irish-British collaboration. An example of such collaboration was the permission for Allied use of Irish airspace for military means.
Sweden's stance during the Winter War: While Sweden did not officially participate in the 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.
The political stances of the US and Peru during the Falklands War and that of the Netherlands during the 2003 invasion of Iraq, which was described by politicians as "political support, but no military support."