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Firefighters attend to the crash site of a military transport aircraft in a field.
Ukrainian firefighters respond to Ukrainian military transport plane shot down during Russian invasion. State Emergency Service of Ukraine | Alamy Stock Photo

Ukraine invasion: why eight Nato members triggered article 4 of the North Atlantic Treaty

In the 73 years since the North Atlantic Treaty Organization (Nato) was founded, member nations have activated article 4 of its founding treaty only half a dozen times. The latest instance was on February 24, the day Russia invaded Ukraine. Eight Nato members – Bulgaria, the Czech Republic, Estonia, Latvia, Lithuania, Poland, Romania and Slovakia – immediately invoked the article, thereby convening a consultation of Nato’s principal decision-making body, the North Atlantic Council.

Article 4 can be triggered when one or more Nato members deem the “territorial integrity, political independence or security” of any of the member states to be threatened. The North Atlantic Council meets regularly to discuss all items on its agenda, from military capability development to operations. When article 4 is triggered, however, the council prioritises the raised issue and discusses it instantly.

Although under article 4, member states do not have any other obligation than to consult, they usually agree on a joint decision or action. By contrast, article 5, which is about the collective defence of the member states specifically, stipulates that “an armed attack against one or more of” the allies “shall be considered an attack against them all”.

Since Ukraine is not a Nato member, article 5 was not relevant: article 4 was the only option. The fact that eight nations triggered it demonstrates the gravity of the situation.

A man in a black suit stands behind a lectern with flags in the background.
Ukrainian president Volodymyr Zelenskiy attends the Ukraine-Nato Commission meeting in 2019. SOPA Images Limited | Alamy Stock Photo

Legal processes

When the North Atlantic Treaty was signed in Washington in 1949, the founders of Nato created these mechanisms to deal with a potential Soviet invasion of western Europe. During the cold war, however, neither article was activated.

Since the fall of the Berlin Wall in 1989, article 5 has been invoked only once, immediately following the terrorist attacks of September 11 2001. This was done by Nato allies the day after Al-Qaeda hijacked several aircraft and crashed them into the Pentagon building in Washington and the World Trade Center in New York, killing almost 3,000 people, to show solidarity with the US and implement a package of security measures.

While article 4 has been invoked more frequently in the past three decades, the current situation remains unique in several ways. Previously, a single member state has triggered it: Turkey did so five times between 2003 and 2020, in relation to the Iraq and Syrian wars. Poland triggered it once, in 2014, when Russia annexed Crimea from Ukraine. What we have not seen before is eight members invoking the article simultaneously.

Protestors hold up a photo of Vladimir Putin and a Ukrainian flag.
Russia’s annexation of Crimea in 2014 saw Poland trigger article 4. Bernal Revert | Alamy Stock Photo

Second, previous events leading to article 4 consultations were, for the most part, unexpected: the Syrian air defence shooting down a Turkish fighter jet in June 2012; the Russian occupation of Crimea in 2014. By contrast, the US and the UK have been warning their Nato allies and Ukraine about the high probability of a large-scale Russian invasion for months.

Thus, although watching the actual Russian military operations unfold in Ukraine has been shocking, it has not been completely surprising. Weeks before the war started, the US and the UK deployed thousands of troops to eastern Nato members, including Poland and Estonia, as a precautionary measure. Kyiv could not get this kind of support because Ukraine is not part of Nato.

Finally, previous article 4 consultations have seen Nato often implement measures. Nato countries deployed Patriot missile systems to protect Turkey against Syrian attacks in 2012. And in 2003, early warning aircrafts, missile systems and over a 1,000 troops were sent to Turkey during the US-led Iraq war.

In this instance, however, Nato has not made any decisions directly linked to the triggering of article 4. This does not mean, of course, that Nato has not responded to the Russian invasion. Quite the contrary.

Nato leaders held an extraordinary virtual summit on Friday, February 25, the second day of the Russian invasion. The Nato Response Force, which comprises 40,000 troops from member countries, has been activated for the first time since its 2003 establishment. In addition, the alliance has also activated defence plans: new US reinforcements have arrived in Europe, and many Nato countries have increased the readiness of their forces.

However, these measures were implemented based on established mechanisms. They probably would have occurred even if article 4 had not been triggered. The relevance of doing so here, though, is that article 4 pushes the war in Ukraine to the top of Nato’s agenda, with immediate effect. Further, the fact that almost one third of Nato members activated the article demonstrates the extent to which many European countries perceive the situation in Ukraine as a severe threat to their security.

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