Former chancellor Rishi Sunak and Foreign Secretary Liz Truss are the final candidates standing in the race to become Conservative Party leader.
The Tory MPs are campaigning to replace Boris Johnson, who resigned earlier this month, and take their place in No 10.
But, what are their voting records on defence?
According to the parliamentary website 'TheyWorkForYou', Rishi Sunak has consistently voted for military action against Daesh (so-called Islamic State or IS) – two votes for, none against, in 2015. Liz Truss has also voted for such operations – three votes for, none against, in 2014 and 2015.
Operation Shader is the operational code name used for the UK's contribution to the US-led mission against IS.
The final towns and cities once held by the militant group were liberated in 2019, but Operation Shader will continue, with IS not being completely defeated as an organisation.
Rishi Sunak and Liz Truss have both voted consistently to replace Trident with a new nuclear weapons system. Mr Sunak voted four times for and none against, in 2016, while Ms Truss voted five times for, none against, in 2016.
Currently, up to four British nuclear submarines, based at Scotland's HMNB Clyde, patrol global waters, carrying Trident thermonuclear warheads as part of the UK's continuous at-sea deterrent.
The Vanguard-class vessels are due to be replaced by the incoming Dreadnought-class in the 2030s – set to be the largest submarines ever operated by the Royal Navy.
Overseas combat operations
Both candidates have voted consistently for the use of UK military forces in combat operations overseas. Mr Sunak's record is two votes for, none against, in 2015. Ms Truss voted six times for and once against, between 2013 and 2015.
Both candidates voted against investigations into the Iraq War – both voted once against, in 2016.
Rishi Sunak has never voted on strengthening the Military Covenant (five absences, in 2020), while Liz Truss has voted a mixture of for and against (three votes for, four votes against, one absence, in 2020).
The Armed Forces Covenant is a promise by the nation to ensure that those who serve or who have served in the Armed Forces, and their families, are treated fairly.
It covers education and family wellbeing, housing, careers, healthcare, financial issues and discount services.