Britain’s prime minister may not – according to some sources – be particularly interested in defence, but the defence community will be very focused on him this week.

Rishi Sunak is due to unveil an update of the UK’s defence and foreign policy on Monday – the same day as he meets with the US president and their Australian counterpart in the US to announce the details of a major new pact to build nuclear-powered submarines.

Two days later, the prime minister will be back in the UK, where Jeremy Hunt, his chancellor, will confirm as part of his budget a widely-anticipated but modest increase in defence spending – well short by several billion pounds of what military insiders believe is needed.

You can expect headlines about the threats and challenges posed, not just by Russia, but increasingly by China. There may even be a hardening of the language to describe Beijing in the “refresh” of the 2021 Integrated Review – the name of the updated defence, security and foreign policy document.

It had referred to China as a “systemic challenge” but this might be strengthened to be more in line with the tone used by the US and Australia. However Mr Sunak is not expected to go so far as to describe China as a threat.

Overall, the refresh is not expected to produce any fundamental shifts in strategy from the original review, drawn up under Boris Johnson.

The update was initiated last year by Liz Truss when she was prime minister and inherited by Mr Sunak, given the war in Ukraine and growing concern about China.

But the current prime minister has so far failed to commit to lifting defence spending above the NATO minimum of 2% of GDP in response to the increased security challenges, unlike his two predecessors.

Growing pressure on Sunak

Mr Johnson had even been planning to push NATO’s 29 other member countries to agree to increase the alliance’s defence spending target by half a percentage point given the need to deter Russian aggression.

Mr Sunak has been under growing pressure since the start of the year to pledge new money for Britain’s armed forces – in particular the army – as plans to fill gaps in their warfighting capabilities did not deliver fast enough to meet the threat.

This was exposed when Sky News revealed that a senior US general had warned Ben Wallace, the defence secretary, that the UK was no longer regarded as having a “tier-one” or top-level army, following decades of cost-saving cuts.

Initially, the Treasury was reluctant to free up more money for defence, given the huge demands on government finances from other areas that are more popular with voters such as health, welfare and education.

In addition, the Ministry of Defence’s dismal track record at delivering value for money with what is already one of the biggest defence budgets in the world means that Treasury civil servants are understandably wary about committing more expenditure, regardless of how persuasive the pleas from the top brass might be.

Yet, Mr Sunak and Mr Hunt – faced with the reality of the biggest war in Europe since 1945 and the lessons from Ukraine exposing the risk carried by Britain’s army, with insufficient stockpiles of weapons and ammunition – have decided to give something.

Money alone is not the answer

The prime minister is widely expected to confirm new money for defence during his trip to the US, where he will hold a three-way summit with Joe Biden and Australia’s Anthony Albanese in San Diego on Monday, while the chancellor will doubtless add his own words during the budget on Wednesday.

The increase will reportedly be £4bn-£5bn over the next two years – less than half the amount that Mr Wallace had apparently been calling for.

But money alone is not the answer.

Successive governments have tried and failed for decades to reform how the Ministry of Defence and its procurement arm – Defence, Equipment and Support – buy kit, from warships and satellites to boots and light bulbs.

No one has so far managed a successful modernisation of this vital function, leaving the UK without the ability to arm its military at the speed of relevance.

This all means, despite what will doubtless be a volley of tough-sounding remarks by Mr Sunak about the need to stand up to Russia and China and the importance of investing in defence, his own military looks set to remain as hollow as his words.