What Will a New Prime Minister Mean for UK Foreign Policy?

Battling it out: Rishi Sunak and Liz Truss take part in a televised debate during the leadership contest. Image: Imageplotter / Alamy

Conversative party members will soon elect a replacement for Boris Johnson. Will his successor’s foreign policy be marked by change or continuity?

As the Conservative party opens voting for the election of a new leader – who will de facto become the next prime minister – much of the debate between the two remaining candidates has been focused on domestic policy issues. But what will a government under Rishi Sunak or Liz Truss mean for UK foreign policy?

Both candidates have had some involvement on the world stage. As foreign secretary and former secretary of state for international trade, Liz Truss has been involved in high-level diplomatic and trade negotiations – claiming a number of trade deals and the release of two dual-nationals from Iran among her successes. As chancellor, Rishi Sunak has hosted the G7 and been responsible for distinguishing the UK in Europe as the largest bilateral donor of aid to Ukraine.

As long-term members of Boris Johnson’s cabinet – and with Johnson still holding some popularity among the Conservative membership – Sunak and Truss are both legacy candidates who will retain a level of continuity on existing policy and defend past government decisions. Nonetheless, there are some nuanced differences between the two.


The most prominent and current foreign policy issue is the war in Ukraine. Supporting President Volodymyr Zelensky was a key focus of Boris Johnson’s premiership, winning him praise from the international community, MPs, the Tory party membership and the electorate. As a result, both candidates are likely to continue this trajectory in the short term.

Rishi Sunak has demonstrated his commitment to Ukraine by signing off large amounts of humanitarian aid funding, even after cutting the UK’s overall aid budget from 0.7 to 0.5% of GDP. Liz Truss has also proved to be hawkish over the invasion, strongly condemning President Vladimir Putin’s actions and promising to support Ukraine’s reconstruction efforts.

The challenge for the next prime minister will be to avoid ‘Ukraine fatigue’ in the longer term. The current state of the economy, compounded by the cost of living crisis and the impending removal of the energy price cap in the autumn, will increase the pressure to focus attention and funding on domestic issues.


76% of Conservative party members voted to leave the EU in 2016. Consequently, both candidates will continue a pro-Brexit line. While Sunak was an early campaigner to leave the EU, Truss has since discarded her Remainer views to become a fierce Brexiteer, leading negotiations with Brussels and denying that Brexit has been responsible for the delays at Dover.

Higher spending on defence and security is always a popular policy among the Conservative membership, and so will remain a core policy for both candidates

Both candidates have promised to scrap hangover EU laws. Sunak initially focused on red tape for businesses and financial institutions, but has more recently promised to establish a Brexit delivery unit to review all EU laws. Truss has also vowed to review all EU laws by the end of 2023. They also both support the controversial Northern Ireland Protocol Bill, which will discard controls agreed in the 2019 EU Withdrawal Agreement, but there is some speculation that Sunak has privately argued against the bill, instead preferring a negotiated agreement with the EU.

Defence and Security

Higher spending on defence and security is always a popular policy among the Conservative membership, and so will remain a core policy for both candidates. The former chancellor has consistently stated that defence spending will only go up, describing the 2% of GDP NATO target as ‘a floor not a ceiling’ and reiterating the government’s current commitment to move to a 2.5% spend.

Liz Truss has gone further and pledged to increase spending to 3%, update the Integrated Review with a renewed focus on China and Russia, and re-examine the shape and size of the UK’s armed forces.

Both candidates have voted to renew the Trident nuclear programme in the past.


Sunak and Truss have made the issue of immigration a key part of the campaign. Appearing tough on immigration is popular with the membership base, and both seek to maintain the controversial policy to deport asylum seekers to Rwanda.

As this policy has been challenged by the European Court of Human Rights (ECHR), Sunak has declared that ‘no options are off the table’ in withdrawing from the ECHR, while Truss has been equally scathing towards the institution, declaring she will not ‘cower’ to it.

Sunak has also argued for changing the definition of qualification for asylum in the UK to allow an annual cap on the number of refugees accepted each year. In addition, he has stated that he will withhold aid from countries that do not accept returned asylum seekers, and has proposed the use of cruise ships as floating detention centres.

Both are attempting to draw upon support as legacy candidates, being mindful of appealing to a specific group of (Tory party) voters where continuity is likely to be preferred

Truss has confirmed that she wants to expand the Rwanda policy to other countries, increase Border Force capacity, and revisit another controversial policy: asking Border Force to intercept channel migrants and tow them back to France.

Energy and Climate

Both candidates have committed to the legally binding target to reach net zero by 2050, with Sunak also putting forward a target for the UK to be energy independent by 2045. However, it remains unclear how these targets will be achieved.

Sunak has suggested that while a ban on onshore wind farms should remain, offshore wind should be rapidly increased. Truss has proposed reviewing fracking and committed to gas as a transition fuel, but there has been little debate on UK energy security in the leadership contest thus far.


One of the most tense debates between the two candidates has been on China. While both agree that China is a threat, each has accused the other of being too ‘soft’. In particular, Truss has pointed out how hard Sunak pushed for closer trade relations, and that Chinese state television had identified him as their preferred candidate. She has also argued that her own record includes countering the Chinese Belt and Road initiative with the G7, providing a clear stance on Taiwan, and condemning abuses in Xinjiang.

In response, Sunak highlighted his advocating of the National Security and Investment Bill to protect against industrial espionage from countries like China, and putting funding in place to welcome those who wanted to leave Hong Kong. He has also announced a plan to close all Confucius Institutes, which teach Mandarin in universities and schools but have links to the Chinese Communist Party.

Overall, the current campaigning shows significant convergence, with only minor differences between the two candidates in relation to foreign policy. This is the result of drawing upon support as legacy candidates and being mindful of appealing to a specific group of (Tory party) voters where continuity is likely to be preferred. The bigger question is whether each candidate will adjust these views in office, and what this will mean for ‘Global Britain’ in the long term.

The views expressed in this Commentary are the author’s, and do not represent those of RUSI or any other institution.

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Dr Louise Kettle FRHistS

Associate Fellow; Assistant Professor of International Relations, University of Nottingham

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