Before the publication of a paper outlining the future of the British armed forces, departing Defence Secretary Ben Wallace said he has not thought about his legacy.
On Saturday, Mr Wallace, who has been Defence Secretary since 2019, said he would stand down as an MP at the next general election.
He said the strain the job has put on his family life was the reason for his resignation.
On Tuesday, the long-awaited defence command paper will be published.
It will set out how the UK will invest another £2.5 billion ($3.27 billion) in stockpiles and a global response force.
Another £400 million will be spent on modernising personnel accommodation.
The report will also outline how investment in science and technology will be given priority as part of an effort to modernise the armed forces.
Despite its publication being one of his last major actions as Defence Secretary, Mr Wallace said he did not think of it as his legacy, but as fulfilling a debt he owed to servicemen and women.
“I don’t think of legacies, I just think it’s the natural step,” he said.
“We started talking about this at the beginning of the year. I was determined that the lessons from Ukraine were brought forward and so that people now know what we need to do, and I think that’s important.”
Ukrainian President thanks UK Defence Secretary for leadership in 'arms and sanctions' - video
Mr Wallace said he arrived in the department with the view it was not “threat-led” enough.
“I’d always arrived in the department with the view that, having been security minister, the department wasn’t threat-led enough," he said.
"It wasn’t responding to threat quick enough. And I think we’ve laid that.
“But this is not about legacy. I owe it to the men and women of the armed forces to import the lessons of Ukraine to make sure where we’re investing we’re doing so on the right track.”
There has been speculation that the paper will recommend cuts to the army’s size, with some reports saying it will shrink from 75,000 personnel to 73,000.
Mr Wallace said the discussion about personnel numbers has been a “distraction from the simple realities”.
“We have carried a force for many, many decades, both under the Labour government and the Conservative government, where we focused on numbers and hollowed out behind," he said.
“That’s not what I’ve ever done as Defence Secretary. I’ve increased the funding – a significant rise in real-term funding to defence.
“I’ve made sure that we were invested in reversing some of that hollowing out, to make sure that what we offer to the government and to the British people is what we can deliver on the tin.
“There is no point having an armed forces just for the parade ground.”
Mr Wallace said he was prepared to speak out as a backbencher if Prime Minister Rishi Sunak did not stick to his promise to increase military spending to 2.5 per cent of GDP in the run-up to the election.
Asked if he would hold Mr Sunak’s “feet to the fire” when he steps down in September, Mr Wallace said: “What I will say is that it is important that everyone sticks to the pledges that they have made.”
He played a key role in the UK’s response to Russia’s invasion of Ukraine.
Mr Wallace's Wyre and Preston North constituency in Lancashire will disappear at the next general election because of boundary changes, and he said he will not seek a new seat.
He is believed to have told Mr Sunak on June 16 of his plans to stand down from Cabinet.
On Monday, Mr Sunak praised Mr Wallace’s “distinguished” career.
