RISHI Sunak pledged the biggest defence boost in a generation - £75billion in the next six years to put the UK on a "war footing".
From nuclear subs and air defences to a more digital-led army, former top military officials told The Sun exactly what the UK needs to build a war chest ready take on the threat of Russia.
As he jetted to Poland for crunch security talks with Nato chief Jens Stoltenberg on Tuesday, the PM unveiled his plan to hike up defence spending to 2.5 per cent of GDP by 2030.
It will raise the annual armed forces cash to £87billion by the end of the decade - a £23billion hike on the current budget.
Sunak hailed it as the “biggest strengthening of national defence in a generation” to combat a growing axis of evil between Russia, Iran, China and North Korea.
“As our adversaries align, we must do more to defend our country," the PM said, adding it marked a "turning point for European security and a landmark moment in the defence of the United Kingdom."
Sunak also unveiled Britain’s largest-ever tranche of military aid for Kyiv (£500million), while warning that Vladimir Putin will not stop at the Polish border should the despot win in Ukraine,
However, the focus now is on how the rest of £75billion will be used to shore up Britain's defences.
Due to be split across the British army, navy and air force, three senior defence figures told The Sun that the money must be spent on restoring the armed forces to a "war fighting capability".
The new defence budget, they said, could not have come soon enough.
General Sir Richard Barrons, former Joint Forces chief, said the money must be spent on the UK's military adapting to a new era of warfare.
From drone fleets, autonomous fighter jets and doubling the UK's reserve army, he told The Sun that UK's forces have to adapt "for a different time with different technology and a different role in Nato."
Firstly, he argued: "We must recognise how absolutely strapped defence is right now - some of this new money is about catching up and paying the actual price of equipment that has already been ordered and some will get lost in the nuclear programme."
The retired military officer said a serious aim should then be investing in preparing defences against any air and missile attacks.
"Look at what Russia does to Kyiv, the UK needs air defences against ballistic and cruise missiles... This is a major risk in the time we are living.
"There is a £4billion solution, focused on industry and reserves to fill this critical vulnerability."
Next, Barrons said the British Army "is the heart of the issue here" and money is needed to provide a "digital backbone" to the force.
After recently being slammed by a Nato general as no longer a "top-level fighting force" and "barely tier 2", the general said: "The army must be restored to a war fighting capability at a reasonable size - which doesn’t mean more people.
"It means equipment, ammunition, training, logistics and doubling the size of our reserve force, which is how it can get to mass when it doesn’t need it everyday."
Barrons also noted: "The army equipment is mostly from the 1990s - we need it updated and quickly."
The RAF is not ready for war fighting against an opponent like Russia
General Richard Barrons
The Challenger 3 tanks could be important, Barrons said, but not as important as long-range precision fires.
"Look at the PrSM [Precision Strike Missile] programme, the range is at 5,000km and soon to be 1,000km."
He also noted the UK has 200 artillery guns. "But Russia has 4,000 in just Ukraine."
In terms of the navy, Barrons argued: "It is short on people and training and ammunition.
"It needs money to adequately prepare to actually fight rather than sail about with the odd missile.
"The future of the navy is not about buying more ships, the future is how it evolves into an unmanned and increasingly autonomous future.
"This is the cheapest, most effective way to get the navy better at war fighting."
In terms of the RAF, Barrons said it has most of the arsenal and planes the US has but "in tiny numbers... This is the bare minimum they could get away with.
"It is not ready for war fighting against an opponent like Russia - so it is not a credible deterrent."
He continued: "The air force is in evolution from a person sat in a cockpit to the aircraft being unmanned - the creation of autonomous aircraft that go faster, turn righter and have greater endurance".
Barrons believes that RAF commanders will ask for more fighter jets, including F-35s. "But I wouldn't buy anymore, they're $100million (£80m) each and they won't be the future."
Instead, he advised that the money should be spent on ammunition, training, spare parts to fly more and "accelerating into a more autonomous capability".
Admiral Lord West praised the new defence budget, but firmly added "it could have come sooner".
At the next Nato summit in July, he said the UK can stand proudly on its promise and put pressure on countries spending less than two per cent on defence.
The former First Sea Lord and Chief of the Naval Staff told The Sun that the £75billion "will make a difference for Putin’s perception...and sets a very good example.
"We can turn up at that Nato summit as a leader within Europe... ready to confront the threat of Russia."
The Falklands War hero argued that plenty of the cash needs to go to updating our nuclear deterrence.
We must look inwards, we have lost the war fighting capability
General Richard Shirreff
In March, the UK confirmed it was developing a replacement nuclear warhead for its Trident missiles.
"These new warheads need to be completed and any future money problems with the programme should be resolved," Lord West added.
The Dreadnought programme - that is developing the future replacement for the Navy's Vanguard class of ballistic missile submarines - "needs to keep marching ahead," he added.
By Jerome Starkey, The Sun's Defence Editor
THERE is an outside chance that Rishi Sunak saved your life.
Love him or loathe him, he has done a good thing — the Prime Minister has ramped up spending on defence.
After months of vapid promises to increase spending “when economic conditions allow”, he finally set out plans to boost the UK’s defence budget to 2.5 per cent of GDP by 2030.
It is not a new plan. Boris Johnson made the same promise at a Nato summit in Madrid two years ago.
The difference is that Sunak put a number on it yesterday. He pledged an extra £75billion for defence over the next six years. That is money for keeping you safe.
In the tinderbox world we live in, it likely means two things.
The best case scenario is it restores our “hollowed out” forces to the point that they can deter our enemies from provoking World War Three, and peace on this island endures.
In the worst case scenario — that war cannot be avoided — a revamped Army, Navy and Air Force will be better placed to win it quickly, alongside Britain’s allies.
Deterrence is the best defence, but it relies on credibility.
It was no good telling Vladimir Putin that we promise to spend more on defence when “economic conditions allow”.
The world is more dangerous now. A tyrant is marching through Europe. The Middle East is ablaze. And China remains determined to retake control of Taiwan.
If you need any convincing, look no further than the bombed-out schools and remains of hospitals in Ukraine’s eastern Donbas.
This is Britain stepping up to its historic role within Nato.
We are showing Russia our resolve, inflicting costs on Putin and teaching Iran and China lessons about how the West can respond when the global order we treasure is threatened.
Ultimately, this investment is about having a credible deterrent, conventional as well as nuclear.
It is about avoiding future conflicts so that you, or your fighting-aged children, are spared the need to fight and die in a bloodbath Third World War.
General Sir Richard Shirreff, the former deputy Supreme Allied Commander in Europe, said that this new package is desperately needed, but has come "too late".
He told The Sun: "We should have been moving to a war footing two years ago with the full-blooded invasion of Ukraine but really we should have woken up 10 years ago.
"Many of us were saying so at the time… and that wake up call was ignored."
The absolute priority of this package, Shirreff argued, is the £500million support for Ukraine. "If Russia forces Ukraine into defeat, it is an existential threat to ourselves".
And for the UK, "we must look inwards, we have lost the war fighting capability."
He suggested the regular army should be increased back to 2010 levels of 100,000-strong as the UK has "lost its war fighting capability".
The regular army currently sits at 73,520 troops.
"We have to expand if we are to deter Russia and demonstrate real determination that we are ready for the worst case."
General Shirreff explained that the ";worst case" is that Putin will force Ukraine into defeat before moving onto new targets - Moldova, Georgia and onto the Baltic states and eastern Poland.
"Then we are all at war with Russia," he warned, adding it could come as soon as three to five years.
With this possibility in mind, Shirreff said the new defence budget "just doesn't cut the mustard... it is too little, too late."
