With tensions escalating with Russia, multiple nations are re-introducing conscription to ease pressure on the professional army – but would the UK?
The UK may need to call up reserves to put boots on the ground in Ukraine, but is facing “real issues” in personnel numbers, former senior officials have warned.
Prime Minister Sir Keir Starmer has said the UK is ready to put “boots on the ground, and planes in the air” to protect Ukraine following a ceasefire.
But Admiral Lord West, the former head of the Navy, said that it could be “extraordinarily difficult” for the military to produce units to act, in Ukraine or elsewhere, amid funding shortages and falling personnel numbers.
Along with a top ex-Ministry of Defence official, Lord West also warned that there was also a serious lack of information about the Strategic Reserves, who could be the third wave of a large-scale, long-term military deployment.
Policymakers have remained tightlipped about the options for deploying a British force in Ukraine, including the amount of personnel and their role on the ground.
Defence insiders said that planning is ongoing to ensure that a multinational force can deploy in the days following the cessation of hostilities.
The plan for any Western power presence in Ukraine will depend on the terms of the peace deal currently being brokered by the US.
But the UK has a three-wave plan for military deployments which give some insight to how the force might be formed – and where the gaps lie.
Wave one: Regulars
In the case of any large-scale military deployment, the first wave to enter a conflict would be the regulars – full-time and highly trained professional military personnel – of which the UK has 125,680.
In comparison, estimates state Ukraine’s military strength is more than 800,000. The US is estimated to have more than one million active personnel; France has 200,000 and Poland has 216,000.
British forces are already supporting a range of UN peacekeeping missions around the world, from Somalia to Cyprus.
The British military has been progressively shrinking, but the Government has vowed to “reverse the long term decline in the size of the Army” by increasing defence spending to 2.5 per cent by 2027 and are providing “better training, smarter use of existing capabilities and harnessing technological advancements”.
Wave two: Volunteer reserves
The second would be the active reserve force; people with civilian jobs who volunteer to commit a portion of their time to military training.
The Volunteer Reserves make up 17.5 per cent of all service personnel, with 31,940 personnel as of October 2025.
The MoD describes the Reserves as “an essential element” in the military, and they are regularly deployed around the world.
Matthew Savill, director of military sciences at RUSI and former senior MoD official, said that the UK may need to call up its reserve forces or pull troops from other commitments in order to staff a Ukraine peacekeeping force.
“Obviously it would depend on the scale and the role, but if we were putting in a large land force that we intended to sustain, that would be a really heavy drain on the Army,” Savill, who was formerly head of the UK’s special forces operations and its Ukraine crisis response team, told The i Paper.
“You could imagine that there would be some mobilisation of reservists – not just infantry, but I actually suspect a lot in terms of intelligence and other special specialisms – if it were to last over several years.”
“That’s unless we would be giving up on our other commitments, and I don’t think we’d want to do that.”
Wave three: Strategic Reserves
In general deployment planning, the third wave would be the Strategic Reserves, made up of former service personnel.
The MoD says this force contains “trained and experienced personnel who can be recalled when the nation needs them most”.
It is comprised of two groups. The first is the Regular Reserve, who are former Service personnel with an ongoing legal liability to train and to be called out if needed, usually for six years after leaving the military.
Numbers within the Regular Reserve are routinely published and stood at 35,897 this summer.
The second group is the Recall Reserves; former service personnel who can be called until age 60 in the case of national emergencies.
The MoD says the Recall Reserves would only be called upon in the in the “direst of situations”.
But the size and readiness of the Recall Reserves is less clear. The MoD does not publish figures on the amount of personnel available to be recalled, although says it does retain records.
“We’ve got a bit of an issue, because we don’t really know what [the Recall Reserves] looks like, where they are, what state they’re in, we don’t know how much of that we can call upon,” Savill said.
Lord West said he did not believe that the UK has “a proper Strategic Reserve.”
“There are real issues over numbers in the Army in particular, but also in terms of engineers and things in the Air Force and Navy,” he told The i Paper.
“In the Army, actually providing the units to do something, if something is asked for, is going to be extraordinarily difficult.
“The bottom line is, you’ve got to make sure that the various levels of provision of support we provide are all actually properly funded and trained and available to go, and I don’t think that’s the case at the moment.”
Lord West said that while defence spending is due to increase by 2027, for the next year or two, the forces are still “desperately short” – hampering any potential recruitment or expansion efforts.
The Strategic Defence Review, a blueprint for improving the state of the UK’s Armed Forces, recommended that the MoD step up engagement with those ex-military personnel with an enduring Strategic Reservist liability.
The MoD is acting on this, saying it is “reinvigorating engagement” with Recall Reserves and to develop a “new Strategic Reserve” by 2030, in order to “build surge capacity for concurrent demands including warfighting and home defence.”
It is currently considering different ways to increase engagement with Strategic Reservists, such as through annual training opportunities, exercises and exploring a digitised approach to Reserves management, The i Paper understands.
Defence insiders said it is also exploring a targeted communication campaign with veterans and their employers.
Wave four: Potential conscription
Conscription is considered a last resort because of ethical concerns and also because conscripted forces are less well trained and tend to perform poorly.
It has only been used twice in British history in the First and Second World Wars, although it continued into peacetime until 1960.
It is not currently being considered in the UK and military experts said any potential use of conscription is still far off.
Savill stressed that conscripted forces would not be on the cards for a Ukraine peacekeeping force.
“You would absolutely not, I think, be conscripting to deploy that force,” he said. “You want a highly trained professional force because it’s going to be operating in a very difficult environment.”
Several of the UK’s allies have conscription, some having reintroduced it in recent years, including Lithuania, Sweden and Latvia, who brought back mandatory military service in 2015, 2018 and 2024 respectively.
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A MoD spokesperson said: “This Government has no plans to introduce conscription in the UK and believe the best way of defending our country is by maintaining professional Armed Forces who choose to serve.”
