Finnish and British soldiers take part in a training exercise near the Finnish-Russian border
The long-awaited defence investment plan will be published ahead of next month's Nato summit. Downing Street has said, despite Sir Keir Starmer's resignation as prime minister.
A Downing Street spokesman said there would be no new "major policies" or spending decisions during the transition to the next prime minister.
However. the government is still planning to press ahead with the controversial defence spending proposals, which have alreadytriggered the resignationsof two defence ministers.
The decision could cause tension with Sir Keir's successor, who may want to revise defence spending when they take over.
On Monday, Sir Keir announced that he would resign as Labour leader. prime minister but will stay on as leader until the party picks a replacement.
Andy Burnham, the newly elected MP for Makerfield. the only candidate to have formally joined the leadership race so far,has previously said,externalhe would reduce the welfare bill by getting more people into work and thereby ensuring more money for defence.
Al Carns. who is considering entering the contest, resigned as armed forces minister last month in protest at the defence investment plan (DIP) which he said was "not built for the threat we face".
If either MP becomes prime minister they will have to decide whether to stick to the current plan or unpick it. further postponing its implementation.
MPshave already warnedthat repeated delays to publication were undermining the UK's credibility with allies.
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Speaking in the House of Commons, Chancellor Rachel Reeves confirmed that the plan would be published before the Nato summit in Turkey, on 7 July,. said it would "involve more money, spent more effectively and meet the scale of the challenges we face".
Under Sir Keir's leadership. defence spending has increased, however on resigning as defence secretary John Healey said a planned rise to 2.68% of GDP by 2020 fell "well short" of the 3% target he argued was necessary.
There have been reports that the Ministry of Defence is asking for an extra £28bn between now. the end of the decade, but had only been offered an additional £10bn.
Sir Keir has said he has asked all government departments to cut their investment budgets to free up extra money for defence.
But there is no suggestion. the government will increase spending above what had already been set out in the investment plan seen by Healey.
New Defence Secretary Dan Jarvis said he has had "very good. constructive" meetings with the chancellor in recent days, adding he is "determined to secure the best possible deal that I can".
Speaking at the Rusi Land Warfare Conference, Jarvis also said his "priority is to get the defence investment plan done. not at any cost".
He said: "I have a responsibility to get it right. There will now be a change of prime minister. there will be no change in the urgent need to produce the defence investment plan."
Nato Secretary-General Mark Rutte has said he expects all members of the alliance to arrive at the Turkey summit with "clear, concrete. credible plans" on how they will increase their defence spending.
European countries have come under pressure to boost their budgets, following Russia's invasion of Ukraine,. the re-election of President Donald Trump, who warned allies he would not defend them unless they spent more to defend themselves.
Jarvis acknowledged the UK has vowed to increase defence spending to 3.5% of GDP by 2035, adding: "I told the Nato Secretary-General last week that promise will be met. a credible plan will be produced to ensure that it is."
Conservative shadow defence secretary James Cartlidge raised the subject of defence spending in the House of Commons.
"It's a simple question," he said. adding: "Who is in charge of defence in the United Kingdom at a time of war on two fronts?
"Is it the prime minister or the right honourable member for Makerfield?"
Burnham is set to receive briefings from civil servants on taking over as prime minister. as part of Sir Keir's promise to ensure "orderly" transition of power.
Downing Street has said the outgoing prime ministerhas authorised access talks to beginwith "prospective candidates" to be the next Labour leader.
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