Jeremy Hunt's spending plans for defence will not allow Britain's "hollowed-out Army to be regenerated", a senior Tory MP has warned.
Tobias Ellwood, who chairs the Commons Defence Committee, said the Chancellor has left "just £1bn a year" to improve the country's conventional forces.
The bulk of the money will be taken up by spending on the nuclear deterrent, Ukraine support and ammunition replenishment, Mr Ellwood said.
His comments echo similar sentiments put forward by the former British Army General Richard Barrons who, speaking prior to the budget announcement, suggested it would take years to overcome the damage that has been done by decades of underfunding of Britain's Armed Forces, thought of as 'hollowing out'.
General Barrons, speaking to Forces News ahead of today's budget, said: "The Army, at current rates of investment, needs at least five years, and more likely 10 years, to be rebuilt in terms of a deployable division, with the people, the equipment, the training and the stocks, to be effective in the face of a confrontation with Russia.
"In other words, we need at least five years' notice of a Russian surprise attack, and that's not a comfortable place to be in the world we now find ourselves."
He also said that "only a tiny difference" had been made in terms of money following the refresh of the Integrated Review.
Mr Ellwood insisted that further cash was needed given the world is "sliding towards a new Cold War" and he urged the Treasury to reconsider its approach.
Chancellor Mr Hunt said the Government would add £11bn to the defence budget over the next five years.
He told MPs: "It will be nearly 2.25% of GDP by 2025. We were the first large European country to commit to 2% of GDP for defence and will raise that to 2.5% as soon as fiscal and economic circumstances allow."
The Budget Red Book, referring to defence spending, said: "This will improve the resilience and readiness of the country's forces, by bolstering our conventional stockpiles, enabling early investment for the Aukus submarine alliance, and modernising our nuclear enterprise."
But Mr Ellwood said the Government's refreshed Integrated Review acknowledged there is a "growing prospect that the international security environment will further deteriorate in the coming years" and the "risk of escalation is greater than at any time in decades".
Mr Ellwood told the Commons: "Now if ever there was a call to move away from peacetime defence spend, that was it.
"I've crunched the numbers already in the Red Book.
"Simply put, away from the Ukraine support, of ammunition replenishment, for the next two years there's £5 billion allocated of which £3bn goes to the new nuclear enterprise – leaving just £1bn a year to improve our conventional forces.
"That will not allow our hollowed-out Army to be regenerated.
"It will not allow all those cuts we saw in the last review to be reversed, such as tank numbers, troop numbers, armoured fighting vehicle numbers, even Typhoon numbers, Hercules aircraft numbers as well.
"We should recognise, and I say this loud and clear, we're sliding towards a new Cold War as Russia and China further align themselves to challenge and exploit the frailty of our global order.
"And as global security further deteriorates, a failure to invest in upgrading our peacetime defence posture now will not only harm our economy as our markets are slowly closed off, it diminishes our voice on the international stage.
"This is not the time to blink, but we must have the political courage backed by our hard power.
"That is what's earned us a permanent seat on the UN Security Council and I urge the Treasury to reconsider their investment in our UK defence posture."