Defence Secretary Gavin Williamson has insisted additional resources are needed for Britain's Armed Forces, as senior Tories demand more cash.
The Cabinet minister told the Commons that the new defence review "isn't aiming to be fiscally neutral", as he bids to resist pressure to make further cuts.
Mr Williamson also said it would be "irresponsible" not to address the threats faced by Britain, as he encouraged Armed Forces chiefs to "have a voice" and speak about them.
He is aiming to complete the defence review by the summer and denied it is "some operation to take money off" the Armed Forces.
Speaking in the Commons, former Conservative leader Iain Duncan Smith asked: "Could he please ensure that we do not repeat the nonsense of, when people say you can modernise, what they actually mean is you cut?"
Mr Williamson said he would try to learn as many lessons from history as possible, adding:
"What we're wanting to do is have the very best Armed Forces that we can have."
"This isn't aimed as being some operation to take money off the Armed Forces. It's making sure we have the Armed Forces - and give them the support - that we need, and [give personnel] the recognition [that] they do one of the most amazing jobs for our country and that is what we hope to achieve as part of this review."
Tory former Defence Secretary Sir Michael Fallon said: "Are you aware that you will have the support of the whole House if you manage to secure additional funding for the pressures this year and next year but then put the defence budget on to a more sustainable footing that allows our Armed Forces to tackle the increased threats that they face without these demoralising rumours of deep cuts?
"The words here are interesting and they're important but what really matters in the end is money - more money."
Mr Williamson thanked Sir Michael for his campaigning to ensure a rising budget for defence, adding:
"We do need to look at getting additional resources for our Armed Forces so they have the capability to protect and truly defend Britain's global interests - both near and far."
The statement comes after weeks of debate and rumours that Mr Williamson wants the Treasury to give the Ministry of Defence more time and money.
Whether or not he's succeeded in securing more funds has not yet been confirmed but he has, it seems, secured five months to make the case for increased military spending.
It had been feared there could be cuts to the Armed Forces and its capabilities.
According to the Telegraph, service chiefs are now expected to make a series of high-profile interventions as they hope to persuade the public of 'rising threats' against Britain.
Following the Defence Secretary's statement, Chief of Defence Staff Sir Stuart Peach said:
"As I have made clear several times, the global security situation continues to deteriorate. We face rising state-on-state competition and challenge, and new risks to our way of life. These are proliferating at an increased rate.
"We need to be ready to contain or confront the threats and risks we face, and therefore we must adapt as early as possible alongside our allies in NATO and beyond in order to keep ahead of our adversaries - this programme will allow us to do just that."
Lord Menzies Campbell and Nia Griffith MP react to the news that Britain's defence and security reviews will be separated
There were reports these would include a cut to the size of the Royal Marines in an attempt to plug a black hole in the defence budget, with ministers also looking at plans to scrap the Navy's two amphibious assault ships - HMS Albion and HMS Bulwark.
But what exactly does this mean?
The defence strand will now be made into a full-blown defence review.
Downing Street explained that "further work is needed in order to modernise defence and deliver better military capability and value for money".
Liberal Democrat Defence Spokesperson Lord Menzies Campbell said it could be recognition of "possible anxiety" within the Conservatives about what may be contained in the review.
He told Forces News:
"Everyone should be worried about pressure on the defence budget [...] in the end Mr Williamson will have to take responsibility for it."
Shadow Defence Secretary Nia Griffith argued that the devil will be in the detail.
The Labour MP said we need to know exactly what the remit on this 'separation' will be and what the contingency plans are if considerably more funding is needed.
"What I don't want to see is that this is just a way of kicking defence cuts down the road."
Speaking to Forces Radio BFBS, Chair of the Defence Select Committee Dr Julian Lewis said he hoped that the treasury could now be 'persuaded' into considering defence in terms of votes in elections but, "for the security of the next generation". He added:
"Defence expenditure in peacetime is like paying the premiums on an insurance policy. You don't like paying them but you're jolly glad you've paid them if ever you have to call in the policy. But that is not seen as attractive in winning the votes..."
By Forces News reporter Laura Makin-Isherwood in Westminster
Ultimately what this announcement provides is breathing space – more time for the MoD to continue to make its case to the Treasury that more money is required.
While many may say this is a win for the Defence Secretary, it's likely he'll still have a big battle on his hands.