In his foreword to the report, UK Prime Minister David Cameron addressed concerns head on, singling out the rise of ISIL and growing instability in the Middle East, along with the crisis in Ukraine, the threat of cyber-attacks and the risk of pandemics as evidence that the world is a more dangerous and uncertain place than it was five years ago, when the SDSR 2010 was published. At that time, the government's major concern was redressing the black hole in the defence budget; while today, priorities are focused on building an armed force that can face and respond to conventional state-based threats as well as threats that do not recognise national borders.
A strategic shift
This need for a more reactive, more mobile force is something that has been gathering pace for some time, and marks what some commentators are calling a strategic shift in the government's defence policy.
"There is a strategic shift going on, in that although we think our forces may have to turn out to fight a war like in 1991 or 2003, the expectation is that in the next ten years [the government] will be more concerned with what is sometimes called 'strategic raiding'," said RUSI director general Professor Michael Clarke in his immediate assessment following the launch of the SDSR. "That means being able to go somewhere short and sharp to do a specialised job - rather than a big traditional ground force job - and then come back. So we expect our forces to be pretty busy, but to be busy in rather new and innovative ways."
Joint Force 2025
A number of key elements announced in the SDSR support this, namely the restructuring of the UK's land forces as part of Joint Force 2025. Two new strike brigades - forces of up to 5,000 personnel fully equipped to deploy rapidly and sustain themselves in the field - will be created. This builds on work established under the previous SDSR's Future Force 2020 plans, with the creation of a highly expeditionary force of around 50,000 troops - up from the 30,000 committed in 2010.
The strike brigades will form part of a war fighting division of three brigades, and will be equipped with the Ajax vehicle (previously known as Scout) currently under development for the army by General Dynamics UK. In the scope of these plans the vehicle will purportedly give the brigades the ability to 'deploy rapidly over long distances', although this is not a capability for which the vehicle was originally designed.
In light of this perhaps, the brigades will also be equipped with a new mechanised infantry vehicle, adding weight to comments the head of the British Army made at DSEI in September 2015 that a programme to acquire such a vehicle was soon to be announced.
In all, the report said, the new division will "double the number of brigades ready for operations"; and that together with 16 air assault brigade - the army's airborne rapid reaction force, specially trained and equipped to deploy by parachute, helicopter and air-landing - the UK will have an improved ability to "respond to all likely threat"'.
The SDSR made clear that the ability for the British armed forces to undertake a large number of small operations simultaneously is as significant a requirement as the ability to deploy on a larger scale.
Investment in special force equipment was outlined as a priority, including upgrades to helicopter and transport aircraft fleets for force insertion and new communications equipment and weapons, with forces to be supported by the intelligence they require via investment in an "advanced high altitude surveillance aircraft". A new special forces task force will also be created, and equipped with the ability to operate and strike globally in hostile environments either alone or as part of an allied force.
The particular concern here is counter-terror operations, but the report suggests that this will no longer fall solely into the remit of special operations task forces. The army will see a number of its infantry battalions reconfigured to provide an increased contribution to countering terrorism and building stability overseas.
Joint Force 2025 will "enhance the armed forces' capability to work alongside the security and intelligence agencies to disrupt threats in the most challenging operating environments worldwide", the report said, reflecting the increasingly blurred line between military and security government agencies in tackling the terror threat.
With the aim of increasing the depth of preventative rather than reactive measures against terrorism, the government will invest an additional £2.5bn - including employing more than 1,900 additional staff and strengthening the UK's network of counter-terrorism experts in the Middle East, North Africa, South Asia and Sub-Saharan Africa - to ensure security and intelligence agencies "have the resources and information they need to prevent and disrupt plots against this country at every stage". Additionally, investment in counter-terrorism police will increase and spending on aviation security will be more than doubled.
With countries such as Russia and North Korea continuing to develop and modernise their nuclear capabilities, the SDSR also reaffirms the UK's commitment to maintaining its continuous at sea nuclear deterrent, along with plans to replace its four ballistic missile submarines.
"Other states continue to have nuclear arsenals and there is a continuing risk of further proliferation of nuclear weapons," the report states. "There is a risk that states might use their nuclear capability to threaten us, try to constrain our decision making in a crisis or sponsor nuclear terrorism. Recent changes in the international security context remind us that we cannot relax our guard. We cannot rule out further shifts which would put us, or our NATO allies, under grave threat."
As part of the continuous at sea deterrent the on-patrol submarine will continue to carry 40 nuclear warheads and no more than eight operational missiles. By the mid-2020s the overall nuclear weapon stockpile will be reduced to no more than 180 warheads in order to meet the commitments set out in the 2010 SDSR.
The report said that four Successor submarines will be acquired in a 20-year, £31bn programme, with the first to enter service in the early 2030s.
This year will show whether the Trident replacement programme goes ahead, with decisions to be made on the final size of the fleet and whether in the context of changing strategic threats and defence budget constraints the programme presents a rational and cost-effective case. A vote on the Main Gate decision will also take place in 2016, and calls for greater parliamentary scrutiny are likely to dominate the issue as it goes forward.
The SDSR 2015 has gone some way to rectifying some of the austere measures introduced by its 2010 predecessor. No cuts and promising plans to invest on significant equipment acquisition programmes is good news for the British armed forces, but although money has been allocated for these various announcements it remains to be seen how it will be paid for between now and 2020.