The largest military investment in 30 years is set to be announced by the prime minister – an extra £4bn a year over the next four years.
The money will fund space and cyber defence projects such as an artificial intelligence agency, and could create 40,000 new jobs, the government said.
Boris Johnson said it would help the UK to “bolster their global influence”.
The Ministry of Defence’s annual budget is around £40bn, so the £16.5bn over four years is about a 10% increase.
The extra spending is on top of the Conservatives’ 2019 manifesto commitment.
Then, the government pledged to increase defence spending by 0.5% above the inflation rate, which is currently at 0.7%, for every year of the current Parliament.
So based on forecasts of inflation, the government said it expects the Ministry of Defence to get a total overall increase of about £24.1bn over four years, compared with last year’s budget.