Foreign Secretary Dominic Raab has said the decision to lift the cap on the UK's stockpile of nuclear warheads represents the "ultimate insurance policy" against threats from hostile states.
The long-awaited Integrated Review, which was published on Tuesday, commits to increasing the number of nuclear warheads Britain has at its disposal to 260 – reversing a move to reduce the stockpile to 180.
The review has been billed as the most radical reassessment of Britain's place in the world since the end of the Cold War.
Speaking ahead of its publication, Mr Raab said it was important to maintain a "minimum credible level of deterrent".
Asked why the Government would want to increase the limit, Mr Raab told BBC Radio 4's Today programme: "Because over time as the circumstances change and the threats change, we need to maintain a minimum credible level of deterrent.
"Why? Because it is the ultimate guarantee, the ultimate insurance policy against the worst threat from hostile states."
The review says a "minimum, credible, independent nuclear deterrent" remains "essential in order to guarantee our security".
But ministers have concluded that, with a "developing range of technological and doctrinal threats", it is not the time to press on with 2010 plans to lower the overall stockpile of nuclear warheads but increase them to "no more than" 260.
The 114-page review also analysed threats to the UK, warning of a "deteriorating security environment" in the world.
It acknowledged the rise of China as a global force and said Russia remains the "most acute threat to our security".
Prime Minister Boris Johnson said the UK must be "match-fit for a more competitive world" as he set out a foreign policy that will see Britain tilt towards the Indo-Pacific region as the world's "geopolitical and economic centre of gravity" moves east.
Further details on how the review will impact the Armed Forces are due to be published on Monday.
The review does commit to Britain deploying "more of our Armed Forces overseas more often and for longer periods of time" for training and exercises.
In a sign that defence spending will shift away from traditional, and expensive, military hardware the report noted "the advantages offered by high-tech capabilities may be eroded by affordable, easily-available, low-tech threats such as drones and improvised explosive devices".
Shadow foreign secretary Lisa Nandy said the review was "riddled with inconsistencies and contradictions" and "there is a yawning gap between this Government's words and its action".
For more discussion on the Integrated Review, click through to this week’s episode of the Sitrep Podcast.
Cover image: HMS Vanguard's DASO Trident missile being launched in 2005 (Picture: MOD).