Cabinet Minister Penny Mordaunt warned that the Royal Navy must “keep pace” with navies around the World otherwise “Britain’s interests cannot be secured”.
And Lord General Richard Dannatt drew parallels with the 1930s when the “woeful” state of the UK’s armed forces failed to deter Adolf Hitler from waging war in Europe.
“There is a serious danger of history repeating itself,” he said.
“If our armed forces are not strong enough to deter future aggression from Moscow or Beijing it will not be a small war to contend with but a major one.”
But Mr Shapps responded to Ms Mordaunt and Mr Shapps’ criticisms: “I’m in a post where there are a lot of people with opinions and a lot of people who’ve been in the military and armed forces will often express them.”
The Defence Secretary said spending on defence will increase to 2.5 per cent “when conditions allow”.
The size of the overall armed forces was around 188,000, Mr Shapps said.
But the size of the Army has fallen to 73,000 and fears are intensifying this could fall further over the coming years.
Mr Shapps admitted the Government is currently prioritising tax cuts over spending more on defence.
He said: “We are committed to spending more when conditions allow. But I also think that it is true to say that people do want to see more of the money that they earn kept.”
Ms Mordaunt, the Commons leader and MP for Portsmouth North, who is also a Navy reservist, linked to a Sunday Times article about the shrinking size of the Royal Navy.
She added: “The Royal Navy and its partners must keep pace with the growing capabilities of other nations. If not Britain’s interests cannot be secured.”
The Defence Secretary said Europe must “step up” and follow Britain’s lead by arming Ukraine with enough weapons to defeat Russian forces.
Mr Shapps said the likelihood of a war between NATO and Russia “is still in our hands” as Western support has helped Kyiv repel Russian forces.
And Mr Shapps urged American and European leaders to send more weapons to Ukraine.
He said: “In the next five years there are a series of concerns, including nation states, including non-state actors, which you could see potentially creating bigger problems.”
“But this is still in our hands. Britain has, again, as with all of those other things, led the way with the £2.5 billion package and a security agreement, a cooperation agreement with President Zelensky and Ukraine.”
“Now, and you ask about America, not just America, but Europe needs to step up and do their part to make sure that Ukraine can continue to defend itself.”
A NATO military chief, Admiral Rob Bauer, said Western allies must prepare for a war with Russia within the next 20 years.
Mr Shapps added: “This is partly still in our hands, in the West’s hands.
We have – we saw Putin invade, he’s been pushed back from 50% of the land that he took in Ukraine, in no small part, because Britain took the leading role in providing training, anti-tank missiles, tanks, long-range weapons; we do things about it.”
