It described what might happen should a hostile state start a fight, saying this could include missile strikes against military sites and power stations across the UK, sabotage of railway lines and other critical infrastructure and attacks on the armed forces.
Politics latest: Britain must be 'battle-ready', says PM
In a devastating verdict on the state of Britain's defences, the Strategic Defence Review (SDR) said today's armed forces are "not currently optimised for warfare", with inadequate stockpiles of weapons, poor recruitment and crumbling morale.
"The international chessboard has been tipped over," a team of three experts that led the review wrote in a foreword to their 140-page document.
"In a world where the impossible today is becoming the inevitable tomorrow, there can be no complacency about defending our country."
The review, which was commissioned by Sir Keir Starmer last July, made a list of more than 60 recommendations to enable the UK to "pivot to a new way of war".
They include:
Increasing the size of the army by 3,000 soldiers to 76,000 troops in the next parliament. The review also aims to boost the "lethality" of the Army ten-fold, using drones and other technologyA 20% expansion in volunteer reserve forces but again only when funding permits and likely not until the 2030sReviving a force of tens of thousands of veterans to fight in a crisis. The government used to run annual training for the so-called Strategic Reserve in the Cold War but that no longer happens.Embracing new technologies such artificial intelligence, robots and lasers. The paper said the UK must develop ways to defend against emerging threats such as biological weapons, warning of "pathogens and other weapons of mass destruction"The possibility of the UK buying warplanes that could carry American nuclear bombs to bolster the NATO alliance's nuclear capabilities. "Defence should commence discussions with the United States and NATO on the potential benefits and feasibility of enhanced UK participation in NATO's nuclear mission."The expansion of a cadet force of children by 30% and offering a "gap year" to people interested in sampling military lifeIncreasing the size of the army by 3,000 soldiers to 76,000 troops in the next parliament. The review also aims to boost the "lethality" of the army 10-fold, using drones and other technology.New investment in long-range weapons, submarines, munitions factories and cyber warfare capabilities.
General Sir Richard Barrons, part of the review team and a former senior military officer, described the vision as "the most profound change" to UK defences in 150 years.
But there were some notable gaps - likely caused by limited finances.
This includes only a brief mention of bolstering the UK's ability to defend against cruise and ballistic missiles - a key weakness but one that would be very expensive to fix.
Earlier today, Prime Minister Sir Keir Starmer said the Strategic Defence Review was a "blueprint to make Britain safer and stronger, a battle-ready armour-clad nation, with the strongest alliances and the most advanced capabilities, equipped for the decades to come".
Defence Secretary John Healey, writing in a foreword to the document, said "up to" £1bn would be invested in "homeland air and missile defence" as well as the creation of a new cyber and electromagnetic warfare command.
The review was drawn up with the expectation that defence spending would rise to 2.5% of GDP this parliament - up from around 2.3% now - and then to 3% by 2034. The government has pledged to hit 2.5% by 2027 but is yet to make 3% a cast iron commitment.
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The reviewers said their recommendations could be delivered in 10 years if that spending target is reached but they gave a strong signal that they would like this to happen much sooner.
"As we live in such turbulent times it may be necessary to go faster," the team said.
"The plan we have put forward can be accelerated for either greater assurance or for mobilisation of defence in a crisis."
The review described the threat posed by Russia as "immediate and pressing".
It said China, by contrast, is a "sophisticated and persistent challenge".
It pointed to Beijing's growing missile capability that can reach the UK and said the Chinese military's nuclear arsenal is expected to double to 1,000 nuclear warheads by 2030.
The other two reviewers were Lord George Robertson, a former Labour defence secretary, and Fiona Hill, a Russia expert and former foreign policy adviser to Donald Trump.
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The review team warned the post Cold War-era of relative peace has ended and a time of contest, tension and conflict has returned.
Adding to the pressure, the US - by far the most powerful member of the NATO alliance - is focusing more on the threat it sees from China.
"Changes in the strategic context mean that NATO allies may be drawn into war with - or be subject to coercion by - another nuclear armed state," the review said.
"With the US clear that the security of Europe is no longer its primary international focus, the UK and European allies must step up their efforts".
The review set out how defence is not only the responsibility of the armed forces because countries - not just the professional military - fight wars.
It said: "Everyone has a role to play and a national conversation on how we do it is required… As the old saying goes, 'If you want peace, prepare for war'."
Sky News and Tortoise will launch a new podcast series on 10 June that simulates a Russian attack on the UK to test Britain's defences, with former ministers and military chiefs playing the part of the British government.