PARIS â Nato is the worldâs biggest military alliance, bringing together 30 European and North American countries who commit to defend each other in the event of attack.
The alliance was formed at the start of the Cold War to protect Western Europe against the threat of Soviet aggression but its remit and reach have expanded over time.
Here is a brief history of the Brussels-based organization:
Countering Soviet threat
The North Atlantic Treaty Organization is founded on April 4, 1949, by 12 countries alarmed by the Soviet Unionâs drive to install communist regimes across Eastern Europe.
The original signatories of the founding Washington Treaty are Belgium, Britain, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal and the United States.
Next to join are Greece and Turkey (1952), West Germany (1955) and Spain (1982).
The treatyâs key Article 5 states that âan armed attack against one or more of them in Europe or North America shall be considered an attack against them allâ.
It requires other members to undertake âsuch action as it deems necessary, including the use of armed forceâ.
Moscowâs response to Natoâs creation is to set up a rival club of 12 communist countries called the Warsaw Pact.
Going to war
After the Soviet Union falls apart in 1991, Nato sets about developing links with former adversaries in Eastern Europe and helping end the Balkans wars.
In 1994, the alliance conducts its first combat operation, sending fighter jets to Bosnia-Herzegovina to enforce a no-fly zone. US fighters shoot down four Serbian aircraft, the first time Nato opened fire.
A year later, the alliance puts boots on the ground for the first time when it deploys peacekeepers to Bosnia.
In 1999, it carries out a 78-day bombing campaign in Serbia over Belgradeâs bloody crackdown on the breakaway province of Kosovo.
Serbian troops duly withdraw from Kosovo, which is placed under UN administration.
The 1990s also sees Nato attempt to break the ice with Russia.
In 1997, the alliance signs a political âfounding actâ with Moscow pledging to build a âstable, peaceful and undivided Europeâ and stressing that they âdo not consider each other as adversariesâ.
In 1999, the first ex-communist countries join Nato: the Czech Republic, Hungary and Poland.
âWar on terrorâ
Natoâs âone for all and all for oneâ pledge is invoked for the first time after the 9/11 attacks on the United States.
Nato joins the US-led âwar on terrorismâ in 2003, taking the lead of the International Security Assistance Force (ISAF) deployed to Afghanistan to root out Al-Qaeda and other Islamist militants.
As the European Union expands, so does the alliance: Bulgaria, Romania, Slovakia and Slovenia join in 2004.
The admission the same year of the three ex-Soviet states of Estonia, Latvia and Lithuania particularly annoys Russia.
Albania and Croatia follow in 2010 and Montenegro in 2017.
Afghanistan and Libya
In 2011, it is given a UN mandate to use âall necessary measuresâ to protect civilians from the fury of embattled dictator Moamer Kadhafi.
Natoâs seven-month campaign of air strikes leads to Kadhafiâs overthrow.
The alliance also contributes to fighting piracy off the Horn of Africa, monitoring human trafficking in the Mediterranean and fighting cyberattacks.
Its combat mission in Afghanistan largely ends in 2014.
But Nato allies only withdraw fully seven years later, sparking a collapse of Western-trained Afghan forces and a takeover of Afghanistan by the Taliban.
âBrain deadâ alliance
Relations between Nato and Moscow suffer a severe setback in 2014 over Russiaâs annexation of Crimea and support for a rebellion in eastern Ukraine.
In 2016, Nato deploys four multinational battalions to Poland and the Baltic states, marking the biggest reinforcement of Natoâs collective defenses since the Cold War.
At the same time the allianceâs relevance is increasingly being questioned, with former US president Donald Trump dismissing it as âobsoleteâ and French President Emmanuel Macron declaring it âbrain deadâ.
In March 2020, North Macedonia becomes Natoâs 30th member.
Russia invades Ukraine
On February 24, 2022, Russia invades neighbouring Ukraine, a Nato partner country that had for years attempted to join the alliance.
Nato urges Russian President Vladimir Putin to end the âsenseless warâ but says it will not send troops to Ukraine.
It rebuffs Kyivâs demands to impose a no-fly zone over the country, fearing being drawn into a confrontation with nuclear-armed Moscow, but agrees to send weapons.
On March 15, Ukrainian President Volodymyr Zelensky says his country should accept it will not become a member of Nato.
Meanwhile, Finland and Sweden, which have been neutral for decades, say they are considering joining the club.
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