It has been the mightiest international military alliance since World War II, staring down threats from Russia and North Korea.

       Its members guarantee a united defence against aggressors. What is Nato and who are its member countries?

       1

       NINNATO is an multi-country defence allegiance Credit: EPA What is Nato?

       NATO is the North Atlantic Treaty Organization. Its 30 members swear to back each other if one of them is attacked.

       NATO was formed in 1948 in the aftermath of World War II, hoping to present a united front against the Soviet Union’s growing power.

       Called a “huge gun club,” NATO draw military might from member states’ arsenals. This includes French, British and American nuclear weapons but NATO prefer “nuclear deterrence.”

       Who are the Nato member countries?

       Nato’s 12 founding members include Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the UK and the US.

       Greece, Turkey and West Germany joined NATO as the Cold War loomed in the 1950s. Spain joined in 1982 and East Germany gained membership by default when Germany reunified in 1990.

       NATO later welcomed Hungary, Poland and the Czech Republic to their ranks.

       NATO ballooned in 2004 with the addition of Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia. Albania and Croatia joined in 2009.

       Most read in News

       SHARK HORROR Brit, 35, mauled to death by 15ft great white as he trained for charity swim

       ANDY FURY Prince Andrew 'shouldn't become ambassador against trafficking', slams charity

       CHEQUE OUT Huge Covid change could cost you ￡500 from next week as PM axes all restrictions

       'PATHETIC' UK's wokest pub slammed after ditching 'unethical' Heineken and Coca-Cola

       Montenegro joined NATO in 2017. In 2020, North Macedonia became NATO's newest member.

       How is the UN different to Nato?

       NATO and the UN are both multinational alliances opposing war.

       However, NATO defends member nations against aggressors if de-escalation is not possible. The UN does not involve itself in combat.

       Most of NATO's 30 members hail from North America or Europe. The UN comprises 193 nations from all over the world, including all NATO member states.

       Is Ukraine part of Nato?

       Ukraine’s potential membership in NATO is controversial. The country’s proximity to Russia means Russian troops are always stationed nearby.

       Invasion from Russia would require NATO nations to respond, potentially setting off world war.

       NATO floated the idea of Ukrainian and Georgian membership in 2008 under pressure from American President George W. Bush. France and Germany opposed. Unanimous consent is required for any nations wishing to join NATO.

       Russian President Vladimir Putin has threatened to invade Ukraine unless the state promises not to join NATO.