NATO without the USA/Canada/Turkey would Defeat Russia if it attacked the UK or any member for that matter.
This takes into effect if the USA sent all of it forces to fight Russia's Eastern & Central Military Districts in the Pacific/Asian Area of Operation. plus is fighting China & North Korea. while having Japan, ROK, Australia, Taiwan, Canada & New Zealand as allies. A conventional World War 3. With the most important theater being the Pacific/Asia Battle Space. Turkey Dropped out because of lack of EU membership and to focus on Dominating the ME.
NATO doesn't have to invade Russia. Nor does the Combined US+ Allies in Pacific have to invade China to wreck either nation. an defeat their Forces. the North Korea, Belarus, Chechen Governments would likely fall in this war. Unless it a short quick war.
NATO by it self outclasses Russia in every metric. from trained forces to equipment, military industry capabilities, economic, population, Logistics to everything.
Russian Combined Forces that would be used in a war vs NATO at first.
2 Military District HQ (Western/Southern)
5 Armies HQ + 1 Deployed (Ukraine)
3 Fleet HQ
2 Air Force HQ
1 Flotilla HQ
3 indep Corps HQ
10 Division HQ
1 Recon Brigades (BDE) + Deployed (1 Ukraine)
6 Tank BDEs
21 Motorized Rifle BDEs + Reserve (2) + Deployed (2 Georgia, 1 Armenia, 1 BG Syria)
2 Marine Infantry BDEs + Deployed (2 Ukraine)
3 Air Assault BDEs
6 Airborne BDEs
39 Total Maneuver BDEs
14 Field Artillery BDEs + 1 Deployed (Ukraine)
3 Rocket BDEs
16 Anti Defense Artillery BDEs + 2 Deployed (Ukraine)
33 Combat Support BDEs
2 Engineer BDEs
1 Military Police BDE
5 NBC BDEs
2 Signal BDEs
1 Electronic Warfare BDE
3 railroad BDEs
2 Logistics BDEs
16 Combat Serve Support BDEs
1350 Modern Tanks
350 Capable Tanks + 80 Reserve + 447 Deployed (Georgia/Armenia/Ukraine)
1700 Total Tanks + 10,200 Capable tanks in deep storage
2800 Infantry Fighting Vehicles (IFV) & APCs + Reserve (240 older models) + Deployed (790)
61 Modern Fighter Jets + Deployed (15 Syria)
371 Capable Fighter Jets + Deployed (42 Ukraine/Syria)
432 Total Fighter Jets
122 Ground Attack Jets (SU24/SU25) + Deployed (14 Syria/Ukraine)
196 Attack Copters + Deployed (27 Syria/Ukraine)
1 Aircraft Carrier
2 Battle-Cruisers
2 Missile Guided Cruisers
9 Missile Guided Destroyers
12 Missile Guided Frigates
36 Corvettes
61 Total Warships
4 Missile Guided Nuclear Attack Subs
12 Nuclear Attack Subs
15 Diesel Attack Subs
31 Total Attack Subs
34 Mine Warfare Ships
15 LST
VS
NATO
1 Unified Command HQ
1 Army HQ
7 Corp HQ
6 Air Force HQ
6 Fleet HQ
25 Division HQ
16 Tank BDEs
66 Mech Infantry BDEs
35 Infantry BDEs
4 Marine Infantry BDEs
6 Air Assault BDEs
6 Airborne BDEs
123 Total Maneuver BDEs
13 Field Artillery BDEs
2 Multi Rocket BDEs
7 Combat Aviation BDEs
12 Anti Defense Artillery BDEs
34 Combat Support BDEs
8 Engineer BDEs
11 Military Police BDE
8 NBC BDEs
9 Signal BDEs
5 Electronic Warfare BDE
7 transportation BDEs
16 Logistics BDEs
11 Military Intel BDEs
8 Medical BDEs
83 Combat Serve Support BDEs
870 Advance Tanks
991 Modern Tanks
1573 Capable Tanks
100 Poor Tanks
838 Hopeless Tanks
3372 Total Tanks
13,000 Infantry Fighting Vehicles (IFV) & APC
32 Advance Fighter Jets
551 Modern Fighter Jets
880 Capable Fighter Jets
20 Poor Fighter Jets
77 Hopeless Fighter Jets
1560 Total Fighter Jets
239 Ground Attack Jets
344 Attack Copters
1 Nuclear Aircraft Carrier
1 Aircraft Carrier
2 Helicopter/STOV Carriers
9 Amphibious Assault Ships (LHA/LHD)
52 Guided Missile Destroyers
2 Destroyers
69 Guided Missile Frigates
4 Frigates
24 Corvettes
164 Total Warships
12 Nuclear Attack Subs
45 Diesel Attack Subs
57 Total Attack Subs
159 Mine Warfare Ships
18 LPD/LSD/LS/LSM