Jeremy Hunt has pledged to spend an extra £15 billion on defence if he is made prime minister to help combat “new threats to western values”.
The Foreign Secretary and Tory leadership hopeful said he would increase funding for the armed forces by 25% over five years to show Britain is “determined to remain a first-rank military power”.
The boost would see defence spending rise from 2% of gross domestic product (GDP) to 2.5%.
The pledge to increase funding comes after repeated complaints by US president Donald Trump over defence spending levels among Nato countries.
Britain is one of a few European countries to meet the 2% target expected of alliance members.
Mr Hunt had previously warned that it was not sustainable to expect the US to carry on spending 4% of its GDP on defence while other Nato allies spent only 1% to 2%.
Mr Hunt said in a statement to Politics Home: “I was the person who secured a historic funding boost for the NHS and as prime minister I’ll do the same for defence.
“Increasing defence spending by 25% over five years will show the world a self-confident country ready to defend its interests and values as we embark on an exciting post-Brexit future.
“Everyone knows Britain is a world-leading soft power, but to be credible we need to show that we are determined to remain a first-rank military power.
“My plan for defence will give our brave troops the backing they need and show the world that when it comes to the new threats to Western values, Britain is back and Britain’s voice will be strong.”
On a visit to Cyprus on Monday, Defence Secretary Penny Mordaunt said defence and investment in the armed forces needed to feature more in the Tory leadership contest.
Welcoming Mr Hunt’s announcement, she said: “We must give the men and women of our Armed Forces what they need to do the job we ask of them.”
Mr Hunt’s pledge comes after warnings of a funding black hole of at least £7 billion in plans for kit for the armed forces.
The Commons public spending watchdog blamed the shortfall on Government dithering over which projects to fully finance, cancel or scale back.