Britain is facing a "similar situation" to the period before the Second World War due to run-down defences, the Commons Leader has warned.
Sir Alan Campbell acknowledged the comparison to the 1930s but insisted the government was working to rebuild the country’s military capabilities.
He told MPs he hopes "what happened later is not something that happens now."
Sir Alan's comments came as he responded to Andrew Murrison, a Conservative former defence minister, who urged the government to publish its long-awaited defence investment plan, which was due last autumn.
The remarks also coincide with the ongoing conflict between the US and Iran, which has reportedly strained the special relationship between the UK and Washington.
Mr Murrison told the Commons on Thursday: “In the late 1930s, this country’s defence industrial base grew very fast indeed to deal with the mounting threat.
“The failure to publish the defence industrial plan is not in that tradition.
“Can we have a debate in Government time to establish when we are going to see the defence industrial plan – whose delay is holding our defence industrial base back – published?”
Sir Alan responded: “We are facing a similar situation to the one that he describes at the end of the 1930s, in that defences were run down, and the decision had to be made in order to start to rebuild them.
“And that’s why the work that he talks about at the end of the 1930s had to happen.
“Of course, we hope that what happened later is not something that happens now.
“But we are trying to rebuild our defences, we are working on the plan, and we will publish it as soon as we can.”
Earlier this month, Labour’s Tanmanjeet Singh Dhesi, the chair of the Defence Select Committee, said investment and certainty were needed to boost military capabilities, amid rising tensions across the globe.
Mr Singh Dhesi said: “The world is rearming at pace, and the United Kingdom is not keeping up.
“We must confront the reality together that national defence requires long-term thinking, stable investment and as far as possible, cross-party working.”
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