Nato leaders will meet in London next week to mark its 70th anniversary, but analysts are questioning whether the alliance is still fit for purpose.
And another question being raised – one that will hopefully never be put to the test – is who would win if the combined military might of Nato went up against an increasingly aggressive Russia.
Research by the Royal United Services Institute (RUSI) found that British forces would be “comprehensively outgunned” in any conflict with Russia in Eastern Europe, The Independent reports.
But the Ministry of Defence says the UK is “well equipped to take a leading role” should Nato come up against opposition forces.
What is Nato’s capability?
The core principle of Nato’s international military alliance is its system of collective defence, meaning if any member state is attacked by a third party, then every member state must step in to defend it.
Fortunately for countries such as Montenegro, which spends just $92m a year on defence, there are some military big hitters in the alliance.
The US spends more on defence than double the rest of Nato combined, with 2019 spending estimated at $730bn, according to the UK Defence Journal.
As well as being the biggest defence spender in the world, the US has a powerful arsenal and a huge amount of manpower – 1.3 million active troops, with another 865,000 in reserve, said The New York Times in 2017.
The UK is the second biggest overall spender in Nato, putting nearly £50bn into defence annually compared to Germany’s £45bn, France’s £42bn and Italy’s £20bn.
Around 800 British troops are currently stationed in Estonia as part of Nato’s “Enhanced Forward Presence” deployment against Russia, says the BBC.
What is Russia’s capability?
Russia’s military capability is not to be sniffed at, easily ranking among the world’s most powerful.
The Kremlin has boasted that Russia has more tanks than any other nation in the world, with some estimates putting the figure at 20,000, more than the whole of Nato combined, says German broadcaster Deutsche Welle.
And Russian artillery and rocket batteries have already proved to be potent – they destroyed two Ukrainian battalions in 2014 within minutes, says the BBC.
However, it is lacking in some areas of modern military technology, including drone capability, electronic components, and radar and satellite reconnaissance, Russian journalist and military analyst Pavel Felgenhauer told Deutsche Welle.
“That’s what the Russian military is talking about: yes, we have weapons, including long-range weapons, but our reconnaissance capabilities are weaker than our attack capabilities,” Felgenhauer said. “So we have-long range, sometimes precision guided weapons, but we don’t always know where the target is.”
Who would win?
RUSI found that the British Army and its Nato allies have a “critical shortage” of artillery and ammunition, meaning they would struggle to maintain a credible defence position if Russia were to opt for all-out aggression.
“At present, there is a risk that the UK – unable to credibly fight – can be dominated lower down the escalation ladder by powers threatening escalation,” said RUSI’s report.
The institute also found that Russia’s air defences could wipe out Nato air support to ground forces in the first weeks of any high intensity conflict in Eastern Europe.
But the MoD said: “The UK’s armed forces are well equipped to take a leading role in countering threats and ensuring the safety and security of British people at home and abroad.”
And the UK wouldn’t need to stand alone against Russia. Nato’s biggest player, the US, has an overwhelming advantage over Russia in conventional forces, Russian military analyst Aleksandr Golts told Deutsche Welle.
It’s a good job. The US is the only thing stopping Russia helping itself to the Baltic states, says Keir Giles, associate fellow with the UK foreign policy think-tank Chatham House.
With the US out of Nato, Russia “would move on the Baltic states more or less immediately”, Giles told Vice. “Putin believes Russian security requires the Baltic states under its domain… we don’t know how exactly an annexation would look, but Russia does practise this scenario. What we do know is it would be over pretty swiftly.”
Of course, a ground or “conventional” war is only relevant if Nato and Russia decide not to go nuclear.
About 1,800 US, Russian, British and French nuclear warheads are on high alert, ready for use on short notice, says the Federation of American Scientists, an organisation that assesses nuclear weapon stockpiles. Russia and the US each have around 1,600 deployed strategic warheads – and many more in reserve.