What is Nato's Article 5 and could a Russia-Poland clash lead to war?

The US has warned Russia against further escalation

A Canadian soldier holds a Nato flag during a meeting of Nato Secretary-General Jens Stoltenberg, Canadian Prime Minister Justin Trudeau, Spanish Prime Minister Pedro Sanchez and other officials at Adazi Military Base in Latvia. EPA

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Russian forces fired cruise missiles at Ukraine’s Yavoriv military training base, 25 kilometres from Poland’s border, on Sunday, killing dozens of Ukrainian soldiers and leading to anxiety in Poland that the war was inching closer.

Russia’s Deputy Foreign Minister Sergey Ryabkov had previously warned any countries supplying military equipment to Ukraine that supply convoys could be “legitimate military targets”, raising the prospect of a Russia-Nato clash.

A violent confrontation between the Nato alliance, several members of which possess nuclear weapons, and Russia — which has about 1,700 nuclear warheads, is unlikely.

Poland is a member of Nato and thus, an attack could trigger Article 5 of Nato’s 1949 founding treaty.

That treaty, according to Nato, represented “a pact of mutual assistance to counter the risk that the Soviet Union would seek to extend its control of Eastern Europe to other parts of the continent”.

Since then, Nato has provided a framework for “collective security,” a concept the organisation says is “at the very heart of Nato’s founding treaty”.

When has Article 5 been used?

For many years, following the break-up of the Soviet Union in 1991, critics of Nato said it no longer had a clear reason for existence.

That changed in 2001 after the September 11 terrorist attacks in New York, when the organisation informed the UN that it would invoke Article 5.

Since then, the organisation has committed joint forces to Afghanistan and, to a much lesser extent Iraq, in the form of a small training mission to help the Iraqi Army.

But the Ukraine crisis has brought the organisation’s original form back to the fore: a conventional military alliance intended to deter foreign state aggression, rather than terrorism.

This role came into focus in 2014 when Russia annexed the Crimean Peninsula in Ukraine and was accused of supplying separatists in eastern Ukraine with arms.

Russia said that it needed to take security action in Ukraine to push back against Nato expansion — Ukraine is not a member of Nato but began talks about joining in 2008, when it applied to start the Nato Membership Action Plan.

Critics of Russia’s position say that after the break-up of the Soviet Union, Moscow signed a treaty with Europe allowing former member states to join any international organisation that they wished.

Either way, Nato is once again posturing itself as a powerful military alliance, warning that any attack on a member will provoke the “collective security” response.

“If there is a military attack on Nato territory it would cause the invocation of Article 5, and we would bring the full force of the Nato alliance to bear in responding to it,” US National Security Adviser Jake Sullivan told CBS News.

Updated: March 15, 2022, 10:21 AM