Almost all warnings and indicators that a wider war is coming are flashing red and it is "breathtaking" that the UK government is failing to better prepare, a top academic has warned.
Dr Rob Johnson, director of the Changing Character of Conflict Centre at Oxford University, said China is taking the steps that would be expected to have the ability to attack Taiwan, while Russia could well be readying to launch military operations against a NATO country.
This comes on top of Vladimir Putin's full-scale invasion of Ukraine, which is in its fifth year, and the US and Israeli war against Iran.
Mr Johnson has compiled a list of 80 "indicators of conflict preparation and coming armed attack" by drawing on the lessons of history, including the run up to the Second World War.
The indicators cover the kind of military activity and hostile diplomacy demonstrated by a nation that is preparing to launch an armed attack, as well as societal changes and government information campaigns.
Asked how many of them are already flashing, Mr Johnson said: "If you look at the whole list, we're about 94%, 95% complete.
"In other words, we're really quite close to the threat of an armed conflict."
Countries that are planning military action typically need time to ready not just their armed forces but their industrial base, economy and population.
Mr Johnson said one early indicator of future belligerence is when a nation starts to significantly expand the size of its navy - something that can take up to 20 years.
There would also be the construction of additional infrastructure to facilitate troop movements or defensive positions.
"You might see railway lines being layered," Mr Johnson said in an interview at his office at Pembroke College. "Tunnels, bunkers, maybe depots being created. It takes time."
Then - closer to an attack - there would be increased military activity, such as training exercises, missile tests, and extra recruitment of personnel.
Diplomatic language would become more aggressive on the world stage, including withdrawing from treaties, recalling ambassadors or severing diplomatic ties.
A government would also need to take extraordinary steps domestically, perhaps by restricting movement, rationing food and fuel, and using TV, radio, and online platforms to promote patriotism and demonise outsiders.
In the final months, weeks or days, you would see the mobilisation of troops towards their intended target as happened when Russia launched its attack on Ukraine in 2022.
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"We saw mobile crematoria being deployed to the border," Mr Johnson said. "We saw, in the last 24 hours, blood banks being delivered to forward medical units. And, because blood is hard to preserve, it's the last indication. You know you've got 24 hours left. They're coming."
As well as plotting the warning signs of war, the academic also mapped out the actions that other nations might be expected to take in response.
"What we end up with is a sort of line of responsiveness," he said.
It starts with monitoring what is happening, then if suspicions grow, it moves to diplomacy and greater intelligence gathering to gain a better understanding of a country's intent.
If the indicators of war continue to flash, rival governments need to put themselves on a war footing too - either to deter any aggression or to be ready to defend themselves in a fight.
In the 1930s, as German defence spending rocketed, the UK took similar action, rapidly expanding its industrial base to be able to produce more weapons, with car factories converted into Spitfire production lines and "shadow factories" built next to existing sites.
Mr Johnson said the contrast with today could not be starker.
Even though war is already raging in the Middle East and Ukraine, he said Sir Keir Starmer has failed to respond with a significant, rapid increase in defence spending coupled with the ramping up of what is left of the UK's defence industrial capacity.
"The lack of preparation I find astonishing. Actually, no, I use the word breathtaking," the academic said.
"I would expect to see a rapid expansion of the Royal Navy, a rapid improvement in munitions production in the UK, co-production with Europe... Crucially, I also would like to see the public being informed properly about what the threat is."
Asked what his warnings and indicators timeline said about the potential threat posed by China, Mr Johnson said: "China is well along that line.
"You've got so-called wolf warrior diplomacy... We've seen the rehearsing, large-scale naval exercises… They have been building, rearming rapidly, massive defence spending…And perhaps most worrying of all, they've made a declaration they're going to have a thousand nuclear warheads by 2030."
As for Russia, even though its forces are fighting in Ukraine, they are also rearming at home.
It means, Mr Johnson said, that the warnings and indicators of a plan for a potential Russian attack against a NATO nation are also evident.
Read more:
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"We're at that moment now, a bit like the winter of 1939, where our key threat actor, Russia, is now ready to attack. They're getting ready. They're at full production of munitions. And we are still hesitating, hoping that perhaps this won't happen."
Sky News is the official media partner of the London Defence Conference 2026. Later this year Sky News will launch a new defence & security app, bringing together video-first reporting from our leading journalists and experts.
(c) Sky News 2026: 'Warning lights for a coming war are flashing red – and Britain is not prepared'

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