Which countries are in NATO and what happens if they’re attacked?
Russia has said the UK is now 'directly involved' in the Ukraine war, claiming its supply of missiles 'cannot happen without Nato'.
Russia has said the UK is now "directly involved" in the Ukraine war, with Vladimir Putin also warning he is entitled to target the military facilities of countries which have supplied weapons.
It comes as the UK is believed to have allowed its Storm Shadow missiles to be used by Ukrainian forces in the Kursk region of Russia, while the US has given permission for its ATACMS weapons to be fired at targets in Vladimir Putin’s country.
The government hasn't officially confirmed whether British weapons had been used by Ukraine in Russia.
In an interview with Sky News, Andrei Kelin, Moscow's ambassador, said: "Absolutely, Britain and UK is now directly involved in this war, because this firing cannot happen without Nato staff, British staff as well." Sir Keir Starmer rejected this in a BBC interview on Friday, saying "we’re not at war".
But what is Nato, and why is it central to the current conflict?
What is Nato?
The North Atlantic Treaty Organization is a political and military alliance of 32 countries "that exists to protect the people and territory of its members".
Its purpose "is to guarantee the freedom and security" of those members "through political and military means".
Why was Nato created?
Nato was set up in 1949 to protect members against the Soviet Union, with 12 nations initially signing up to the North Atlantic Treaty in Washington DC.
These countries were the US, Canada, the UK, Belgium, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway and Portugal.
Which countries are members?
The 32 members, in alphabetical order, are: Albania, Belgium, Bulgaria, Canada, Croatia, Czechia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Lithuania, Luxembourg, Montenegro, Netherlands, North Macedonia, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Türkiye, United Kingdom and United States.
Is Ukraine a part of Nato?
No. Ukraine is only a "partner country", which means it "cooperates closely with Nato but it is not covered by the security guarantee in the alliance’s founding treaty".
Ultimately, this means Nato is not treaty-bound to defend Ukraine.
But membership has been mooted as far back as 2008, with president Volodymyr Zelenskyy pressing the issue again following Russia's invasion in 2022.
And following Nato's summit in July, it said an invitation will be made once members have agreed "conditions are met" surrounding democratic, economic and security reforms.
What happens if Russia or another country goes to war with Nato?
Technically, it would mean Nato would respond in kind.
This is because of Article 5, the collective defence clause of Nato's founding treaty. It means an attack against one member is considered an attack against all of them.
As a result, each member would "take the actions it deems necessary to assist the ally attacked".
This is not necessarily military action: it "depends on the material resources of each country" and "it is left to the judgment of each individual member country to determine how it will contribute."
Last year, Vladimir Putin said Nato troops on the ground fighting the Russian army would be "a very dangerous step that could lead to a global catastrophe".