The troop numbers Europe would need to withstand a Russian invasion

To ask how many troops Europe would need is really to ask three separate questions.

First, how quickly would Europe need to stop a breakthrough on the eastern flank before Russia could present NATO with a fait accompli, either by seizing territory or by forcing a political crisis inside the Alliance.

Secondly, what depth of forces would Europe need to sustain a long, grinding, high-intensity war, where losses are not measured in dozens but in thousands, and where brigades are rotated, rebuilt and returned to the line.

Thirdly, how much of Europe’s “force” must be standing forces (full-time, trained, equipped, ready today), and how much can sensibly be held in reserve, on the assumption that mobilisation works, stocks exist and transport networks function under missile attack.

The most useful way to frame this is not to “match Russia soldier-for-soldier” (a trap, because Russia can throw manpower at problems in ways most European democracies will not), but “deny Russia the prospect of rapid success and then sustain the fight”. That is how deterrence becomes credible.

A practical benchmark for “ready now”

NATO’s own public planning language points towards a large pool of forces at high readiness. NATO has stated an intention to have over 300,000 troops on high readiness under the new NATO Force Model, replacing the older, much smaller NATO Response Force concept. 

That 300,000 figure is not “Europe’s whole requirement”. It is a rapid-response pool across land, air, sea and other domains, pre-assigned to defence plans. But it is a useful indicator of the scale of trained, equipped, deployable formations NATO believes she must be able to move quickly, before mobilisation and industrial surge can do their work.

If we translate that into what Europe (including non-EU NATO members) would need in standing forces to withstand invasion, two realities stand out.

• The eastern flank must be able to fight immediately with national forces that are already in place, because even a well-designed reinforcement plan collapses if the first week is lost.

  
  

• The major Western European economies must provide depth: not merely “token brigades”, but divisions, sustainment, ammunition, air defence, engineering and replacement systems that keep the front supplied and rotating.

A defensible target for Europe’s standing forces

Europe already has substantial numbers in uniform, but they are unevenly distributed, and in many countries the bottleneck is deployable land combat power rather than headcount.

Using the International Institute for Strategic Studies-based active-duty figures compiled in a widely used reference table (which also records reserves and paramilitaries), Europe’s active numbers (counting the armed forces, not just armies) are roughly as follows across the states listed below. 

On that basis, a reasonable planning target for “withstanding invasion” is:

• roughly 2.9 million active personnel across European states excluding Ukraine (who is already mobilised at war scale), up from about 2.0 million today on the same counting basis, with the increase concentrated in land forces, air and missile defence, logistics and engineering

  
  

• and, alongside that, reserves that are genuinely trainable, equipable and recallable, because a continental war is not won by standing forces alone

This is not a prediction that Europe must permanently militarise her societies to Cold War levels. It is the logic of being able to absorb the first strike, then fight a campaign of months and years rather than days and weeks.

Current active forces and an indicative “invasion-resilience” target by country

The “current” column below uses the active-duty figures in the IISS-based reference table. 

The “target” column is an indicative standing-force level aimed at making Europe capable of stopping and then sustaining the fight, with larger increases on the eastern flank and in the largest economies (which must provide depth, enablers and rotation forces).

Country	Active today	Indicative target	Change
Albania	7,500	12,000	+4,500
Austria	22,200	35,000	+12,800
Belgium	23,500	40,000	+16,500
Bosnia and Herzegovina	10,650	15,000	+4,350
Bulgaria	36,950	60,000	+23,050
Croatia	16,800	25,000	+8,200
Cyprus	12,000	15,000	+3,000
Czech Republic	26,600	45,000	+18,400
Denmark	13,100	25,000	+11,900
Estonia	7,100	15,000	+7,900
Finland	23,850	50,000	+26,150
France	202,000	270,000	+68,000
Georgia	20,650	30,000	+9,350
Germany	179,850	260,000	+80,150
Greece	132,000	150,000	+18,000
Hungary	32,150	50,000	+17,850
Iceland	0	0	0
Ireland	9,500	15,000	+5,500
Italy	161,850	220,000	+58,150
Latvia	6,600	15,000	+8,400
Lithuania	16,100	25,000	+8,900
Luxembourg	1,100	2,000	+900
Malta	1,700	3,000	+1,300
Moldova	5,150	15,000	+9,850
Monaco	250	250	0
Montenegro	2,885	5,000	+2,115
Netherlands	33,650	60,000	+26,350
North Macedonia	8,000	12,000	+4,000
Norway	25,400	45,000	+19,600
Poland	164,100	250,000	+85,900
Portugal	26,050	40,000	+13,950
Romania	69,900	120,000	+50,100
Serbia	28,150	50,000	+21,850
Slovakia	15,850	30,000	+14,150
Slovenia	6,200	12,000	+5,800
Spain	122,200	160,000	+37,800
Sweden	14,850	40,000	+25,150
Switzerland	21,300	30,000	+8,700
Turkey	355,200	450,000	+94,800
Ukraine	730,000	750,000	+20,000
United Kingdom	141,100	200,000	+58,900

These targets imply an increase of roughly 0.9 million active personnel across the countries listed, with most of the growth in states that either sit on the likely axes of advance (Nordic, Baltic, Poland, Romania and the Black Sea region) or must generate the heavy enablers and replacement capacity (Germany, France, the United Kingdom, Italy and, in a different theatre logic, Turkey).

Why the targets tilt east, even though the money tilts west

The eastern flank needs mass that can fight immediately: air defence crews, artillery, engineers, electronic warfare, trained infantry, territorial defence formations with full-time cadres and command structures that do not have to be invented after mobilisation.

But the Western European powers must produce what Ukraine’s war has made painfully plain.

• A front consumes ammunition faster than peacetime establishments imagine.

• Equipment breaks, is captured, is abandoned, or is destroyed.

• Battalions that fight must be rotated, or they simply dissolve.

So the “extra personnel” Europe needs are not merely riflemen. In fact the critical European deficit is often in the supposedly dull categories: maintenance, transport, bridging, rail movement, medical, signals, air and missile defence, and the headquarters staff who make large formations function at all.

This is one reason the NATO high-readiness target matters: it is an implicit demand not just for numbers, but for readiness, movement and sustainment. 

Comparing Europe with Russia: what matters, and what does not

On the same IISS-based reference, Russia is shown with 1,134,000 active personnel (and very large reserve totals), although that figure is for the whole armed forces and related categories in that compilation, not a neat measure of deployable manoeuvre brigades. 

Even if Europe were to equal Russia’s active headcount, that would not automatically translate into battlefield parity. The decisive variable is not how many people are on the payroll, but how many equipped battalions and brigades can be generated, moved and sustained, with enough air defence to survive and enough ammunition to keep fighting after the first month.

That is why the targets above deliberately push some countries well above today’s levels: they are, in effect, a personnel skeleton for the kind of force generation system Europe would need if she intended to make a Russian invasion fail quickly, rather than merely making it expensive.

The uncomfortable conclusion

Europe can probably deter and defeat a Russian invasion, but not by pretending that small professional armies, shallow reserves and low stockpiles can be willed into wartime performance at the moment of crisis.

If Europe wants to be able to withstand invasion without betting her future on perfect warning, perfect mobilisation and perfect transatlantic politics, then she needs:

• larger standing forces, particularly on the eastern flank

• much stronger combat support and combat service support across the larger economies

• and reserves that are not merely “on paper”, but trained and equipable

The table above is not a prophecy, and it is not a mobilisation plan. It is a statement of scale: roughly an additional 900,000 active personnel across Europe, concentrated where geography and logistics make the first weeks decisive.