The unavoidable national security questions facing any Prime Minister

Starmer visits HMS Prince of Wales in April 2025. Image: Flickr/No.10

It is often said in politics that the first actions a Prime Minister takes are the most significant— a criticism that the current PM is probably familiar with. 

But this is quite literal. Indeed once all the clapping, shaking hands with the Cabinet Secretary and warm smiles are done, the Prime Minister does a very specific thing. They sit down, and writes four identical letters. Known as letters of last resort, they are identically worded, and are written for the captains of each of the UK’s four nuclear submarines. It marks a morbid twist from the levity of entering office—  the letters are instructions for what to do in the event the entire UK government apparatus is destroyed in a nuclear attack. Various commands can include to retaliate, stand down, follow the lead of a foreign country, or allow the captain to exercise their own discretion. 

The letters are never made public. They are destroyed when each PM leaves office, and their contents are not known to anyone except the PM. Only James Callaghan has revealed his instructions, to reluctantly order a retaliatory strike. And one would hope any new (or reinvigorated) Prime Minister would heed the metaphor created by these first actions as PM— that national security must take priority. Because for all of the political psychodrama that has dominated Westminster for the last few weeks and months, there are serious, quiet, questions surround the national security architecture that any PM has to address. 

Prime Ministers are faced with two types of problems— the ones they want to confront and the ones that they have to. National security generally tends to fall under the latter. Recent developments in the last few months mean that for all of the political questions that will be asked of Prime Ministerial hopefuls on tax, infrastructure, cost-of-living, populism and more, the eminence of of national security quietly hangs over the UK government apparatus, with massive implications. 

Should there be a new Prime Minister, the UK’s international standing and reach of foreign relations would no doubt be a top consideration of the new officeholder— but this is far less ministerial than it would seem. Starmer’s foreign policy ‘reach’, and his ability to move with agility on the international stage stems from a close group of aides that are arguably a single point of failure within the Labour government apparatus. Jonathan Powell, as National Security Advisor, holds enormous influence, and on occasion been referred to as the “real Foreign Secretary”. However, as much as “real (insert ministerial role)” is an overplayed media taunt, Powell’s influence on the UK security/foreign policy global community is widely recognised. He is known to possess wide reaching and deep influence in foreign policy circles, having cultivated close relationships with the Ukrainian government, and even “coached” Zelenskyy on repairing relations with the US administration in the wake of the famous Oval Office scene.  Powell is well respected amongst the Trump administration, having also formed relationships with his (former) counterpart Mike Waltz prior to Trump’s inauguration, in addition to meeting Susie Wiles alongside Morgan McSweeney. 

His position is unique given that he is the first politically-appointed National Security Advisor (traditionally a civil servant role). Resultingly, whilst like his civil servant counterparts he is DV cleared with STRAP3 access, he reports directly into the Prime Minister and does not technically manage the National Security Secretariat in the Cabinet Office— something that falls to the Executive Deputy National Security Advisor Matthew Collins.  

And separately, the Labour Party’s Henna Shah has played a close role in the UK’s strategy. Her proximity to the Starmer political operation is potent— advising McFadden in opposition (who was himself National Campaign Coordinator), and latterly as Starmer’s Director of Party Relations until March 2025. Since then, she has worked closely with Powell, responsible for managing the political reception of the UK’s national security/foreign policy strategy particularly amongst the PLP— a task of remarkable size and importance in these trying times. Likely as a product of both factors, she is one of the few advisors in the Policy Unit to have survived the waves of change that the rest of the Number 10 operation has fared. 

The PM is thirdly reliant on his Private Secretary for Foreign Affairs Ailsa Terry. Recalled from Malaysia in August 2024 to serve in his Private Office, Terry has been a staple of bilateral meetings and was, alongside Powell, the only other British official attending the Starmer-Zelenskyy bilateral at the EPC summit in Armenia. Whilst her status as a civil servant makes her retention much more likely, Private Secretaries for Foreign Affairs are traditionally on secondment to the Cabinet Office/No.10 from the Diplomatic Service (Terry herself was recalled from Malaysia to serve as PSFA), thus making yet further turnover not-improbable. Despite the greater stability of civil servants, the role’s sheer importance in foreign affairs means that the officeholder plays an incredibly powerful, if understated role in the shape and nature of UK national security and foreign relations— making who the officeholder is all the more important. 

More generally, the power and proximity of the Prime Minister’s politically-appointed foreign policy aides (such as Powell and Shah) raises the stakes over whether they would keep their jobs or even follow the boss out of Number 10. In Powell’s case, he is unlikely to have the same proximity to the PM, whom he reportedly has (rare) unrestricted access too and regularly travels with, including to Coalition of the Willing summits, various Trump bilaterals and Starmer’s recent Gulf trip, to name a few. Moreover, following the departure of Morgan McSweeney and Tim Allan, various outlets even reported Powell considering stepping down from the ‘fixed term’ appointment as NSA by the end of the year. Indeed, a general exodus of No.10 foreign policy aides would have significant and severe implications for the UK’s soft power within diplomatic and domestic political networks. 

Powell’s purported replacement, however, is Dame Barbara Woodward, the second of two Deputy National Security Advisors. Nicknamed “Beijing Barbara” over her critics’ accusations that she failed to criticise China during her tenure as ambassador, the moniker itself also illustrates the question of a longer-term UK foreign policy tilt. The UK’s recent reengagement with China reactivated the dormant question of what the UK’s long-term relation with the superpower looks like— both approving the super-embassy by one count and then banning government devices from being taken to China and destroying all the burner devices that officials were forced to use on the state visit in January. Moreover, whilst the Intelligence and Security Committee published its flagship Iran Report in summer of last year, it is now widely accepted that the scale of attacks on Iran has severely changed the power structure of the regime, and thus the accuracy of UK intelligence in the region.

In classic intelligence style, this is quietly, but ever increasingly, being made clear to the public. For the first time in the modern era, (with the exclusion of the MoD’s Defense Intelligence), the heads of all intelligence agencies gave annual addresses— Blaise Metreweli of MI6 and MI5’s Ken McCollum in October 2025, and GCHQ’s Anna Keast-Butler in May 2026. All invoked the notion of being between peace and war. All highlighted the need for political vigilance in the wake of rising attacks and threats to UK infrastructure, sometimes tactile, sometimes digital, always present. 

Much of this is increasingly political. The National Security Council’s decision to delay granting basing permissions for US bombers attacking Iran meant that Executive Deputy National Security Advisor Matthew Collins got “both barrels” from his American counterpart at the State Department. Whilst much of the ‘deep state’ relationship is classified, the UK has reduced sharing Caribbean intelligence with the US over fears its airstrikes on drug-smugglers are illegal, despite the intertwinement of the UK and US’ security postures. The UK and US intertwinement is relatively unspoken of— the most prominent reference has been Blair’s recent admission that America remains the “indispensable core” of Britain’s security alliance. 

This is further complicated by the growing influence of the soft-left, given their less conciliatory legal positioning (particularly Hermer and Miliband), both of whom, as NSC members, took a much more reserved approach to granting access to UK bases for American retaliatory strikes. This intensifies problems when considering the sketchy legal record of recent American operations which the UK commits to sharing intelligence on, and more generally broods questions over internal conflicts regarding any future UK-US military action under a Trump presidency and soft-left UK government. 

And none of this is complete without the much anticipated Defence Investment Plan, first published as the Strategic Defence Review over a year ago, and yet to be financed. With civil servants reportedly pushing for a settlement before the NATO summit in July 7th, it is likely to remain a defining act of Starmer’s premiership, not least thrust into the spotlight by John Healey’s resignation. However, the scope of the settlement is likely to come under criticism— defence chiefs walked into Downing Street in January claiming a 28bn shortfall in funding, and like any spending decision, the outcome has become increasingly polarised. 

Not that funding is without question across the wider national security apparatus. Funding cuts to the Foreign Office recently saw half of the Iranian intelligence team asked to take voluntary redundancy, whilst cuts under former Permanent Secretary Olly Robbins were described as “brutal”. Robbins’ sacking (as well as the dismissal of Deputy Ambassador to the US James Roscoe over leaks) have no doubt shaken the Foreign and Diplomatic Service’s relationship with the centre of government, a relationship that cannot afford anything other than resolute strength. 

Thus several questions face any Prime Minister. They must firstly decide whether defence is a rhetorical or actual priority, and will no doubt be under serious pressure to increase funding regardless. Secondly comes the question of how the politics of the day will shake-up the individuals involved— who is kept, who changes roles, and the direct impact this will have on the UK’s national security posture and interpersonal relations across intelligence agencies and foreign ministries, the importance of which cannot be understated and which are currently relied upon. None of this includes the intense trade, economic, diplomatic and industrial impacts that a much needed clear, long-term national security strategy will set. 

Ultimately, none of these problems have easy answers. Nor would their solutions be easily swallowed by an impatient electorate. But any Prime Minister would to well to heed the advice of Blaise Metreweli, C at MI6:  

“It’s not what we can do that defines us. It’s what we choose to do”.