Defence Secretary Grant Shapps has said he wants the new NATO target for defence spending to increase from the current 2% of gross domestic product to 2.5%.
Mr Shapps said it would make a “real difference” if the countries signed up to the military alliance met his proposed target.
He told Kay Burley on Sky News: “We’re now saying we think that should be 2.5%. We think in a more dangerous world that would make sense.
“I will be arguing that, and I know that the prime minister feels strongly about it, when we go to the NATO 75th anniversary summit which is in Washington DC.”
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The defence secretary’s intervention comes after Rishi Sunak pledged to increase UK defence spending to 2.5% of GDP by 2030 to tackle the “growing threats” posed by hostile states including Russia, Iran and China.
Speaking alongside NATO Secretary General Jens Stoltenberg at a press conference in Warsaw yesterday, the prime minister said he planned to steadily increase defence spending by the end of the decade, rising to 2.4% a year until 2027-28 – then hitting 2.5% by 2030-31.
Funding will rise from £64.6bn in 2024 to £78.2bn in 2028, and then jump to £87bn in 2030-31.
The government has said the commitment amounted to an additional £75bn in funding over the next six years and would see the UK remain “by far the second largest defence spender in NATO after the US”.
Mr Shapps, who replaced Ben Wallace as defence secretary last August, has previously warned it was “critical” for NATO allies to increase their defence spending to at least 2% of national income.
In a wide-ranging speech at the beginning of the year, he warned the world could be engulfed by wars involving China, Russia, North Korea and Iran in the next five years.
The defence secretary repeated that warning today and said the current 2% target was out of date because we “didn’t have the significant rise of China, North Korea now nuclear-armed, Iran attacking and using its proxies… and a very much less stable world given Russia’s full-scale invasion of Ukraine”.
A 2.5% target would pile an extra £135bn a year into NATO’s defence budget, he said, and “would make a real difference”.
Mr Wallace, who was the longest-serving Conservative to head the Ministry of Defence, said his successor should be “saluted” for securing the 2.5% spending commitment – something he had previously called for.
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The former defence secretary said he was “pleased” by the government’s promise to raise defence spending and said 2030 was the “right timescale”.
Labour’s shadow attorney general Emily Thornberry said her party would continue with the 2.5% of GDP spending commitment if it had a “plan as to where we are going to get the money from”.
She accused the prime minister of overseeing a “gimmick” in the run-up to the election, adding: “They should not be allowed to say that they can spend £146bn getting rid of National Insurance without saying where the money is coming from and they shouldn’t be able to say that they can spend £75bn on defence by 2030 without saying where the money is coming from.”