Nearly all of the countries involved in World War II chose to align with one of two massive international alliances: the Hitler-led Axis Powers or the Allies, which eventually evolved into the modern United Nations. However, not every country chose a side—at least not overtly. A handful of states, known as neutral powers, chose not to ally with either side during the war. These nations took a neutral position in an attempt to avoid being attacked, invaded, and/or occupied.
This strategy often failed. For example, Denmark, Belgium, Norway, Luxembourg, and the Netherlands had all established policies of neutrality prior to the start of the war. Yet, Germany ignored these intentions and invaded all five countries on April 9-10, 1940. Soon after, the Soviet Union forced the theoretically neutral nations Lithuania, Estonia, and Latvia into treaties that led to the Soviets occupying and ultimately annexing all three countries. Once occupied, many countries were forced to cede control of their trade partnerships, territory, resources, and military bases to their occupiers, even to the point of allowing their citizens to be conscripted as soldiers in their occupiers' armies.
Most nations that declared their neutrality still helped or rallied behind one side or the other. Portugal, Sweden, and Switzerland all helped the Allies by providing brigades of volunteer-only soldiers, and Sweden helped the Allies crack a secret German code. Spain, Sweden, Portugal, Switzerland, and Turkey all sold raw materials to the Axis powers during that same time, and Sweden allowed Nazi troops free passage through its territory. Argentina, Sweden, and Switzerland, in fact, were three of only a handful of countries that managed to support both the Axis and the Allies in various ways.
The United States also declared its neutrality at the beginning of the war, and managed to remain neutral for more than two years while also finding creative ways to funnel supplies, ammunition, and even planes and warships to Great Britain and its allies. Eventually, however, the attack on Pearl Harbor in 1941 forced the United States to retract its neutrality and officially enter the war.
|Afghanistan||Remained neutral, but traded with Axis|
|Andorra||Remained neutral, but served as smuggling route for Axis|
|Argentina||Remained neutral, but maintained trade relations with UK and allowed Argentinians to volunteer to serve in Allied forces. Technically declared war on Japan, and by extension Germany in March. 1945, but the war's outcome had already been decided and Argentina took no military action|
|Bhutan||Remained neutral, but sent India "friendship gift" of 100,000 rupees at start of war|
|Estonia||Remained neutral, but was occupied by both Russia, which established a puppet government and annexed the state; and Germany, which conscripted thousands of Estonians into the German army|
|Iceland||Remained neutral, but was occupied first by the U.K. and later the U.S. and cooperated with its occupiers|
|Iran||Remained neutral, but refused to expel German residents and was subsequently invaded and occupied by Britain and Russia|
|Ireland||Remained neutral, but did send fire engines to England and share intelligence and naval repair yards with Allies|
|Latvia||Remained neutral, but was occupied by both Russia and Germany and eventually annexed by Russia|
|Liechtenstein||Remained neutral, gave asylum to both Jewish refugees and pro-Axis Russian soldiers|
|Lithuania||Remained neutral, but was occupied by and eventually annexed by Russia|
|Monaco||Remained neutral, but was occupied by Italy and Germany, secretly warned suspects when German Gestapo was on the way to arrest them|
|Portugal||Remained neutral, but sold tungsten to Germany (but in limited amounts), allowed U.K. and U.S. to build/use bases in Portuguese territory (which arguably flipped its status from neutral to "Allied non-combatant"), served as safe haven and transit point for Jews seeking to escape Nazi persecution|
|San Marino||Remained neutral, very briefly occupied when battle spilled into San Marino's territory, technically declared war on Germany in late 1944, but to no great effect|
|Saudi Arabia||Remained neutral, but sold oil to Allies and allowed U.S. to build airbase on Saudi land. Technically declared war on Germany in Feb. 1945, but the war's outcome had already been decided and Saudis took no military action|
|Spain||Initially claimed neutrality, but then switced to "non-belligerent" and assisted the Axis with tungsten and volunteer troops, re-establised neutrality once it became clear Axis were likely to lose|
|Sweden||Began neutral, but switched to "non-belligerent" and sold iron to Axis and reluctantly allowed Axis forces to pass through Swedish territory, shared intelligence and later airbases with Allies, took in refugees, leased naval vessels to Britain,|
|Switzerland||Remained neutral, but captured any soldiers from either side who landed at Swiss airfields, shot down aircraft from both sides that violated its airspace, and maintained trade and financial relationships with both sides.|
|Turkey||Remained neutral, but signed friendship agreements and sold chromite to both sides. Technically declared war on Germany in Feb. 1945, but the war's outcome had already been decided and Turkey took no military action|
|Vatican City||Remained neutral as it was legally bound to do by the Lateran Treaty of 1929|
|Yemen||Remained neutral despite pre-existing alliance with Italy|
Several countries remained neutral during World War II, including Afghanistan, Andorra, Argentina, Bhutan, Estonia, Iceland, Iran, Ireland, Latvia, Liechtenstein, Lithuania, Monaco, Portugal, San Marino, Suadi Arabia, Spain, Sweden, Switzerland, Tibet, Turkey, and the Vatican City.