Odgovora na to vprašanje nihče ne pozna. Najbrž tudi ne sam Vladimir Putin. Nihče ne ve, kje je tista rdeča linija, po kateri bi Rusija začela z uporabo kemičnega ali jedrskega orožja. Nihče ne ve, ali je to močnejši neposredni angažma ZDA v Ukrajini, ukrajinski napad na cilje v Rusiji, ukrajinski napad na Krim ali možnost, da Rusija izgubi v ukrajinski vojni. Dejstvo je, da se zaenkrat tako Rusija kot ZDA držita neformalnega protokola, da prva v Ukrajini ne uporablja “prepovedanih” orožij, kot je kemično in da ne napada ciljev izven Ukrajine, druga pa, da izrecno pazi, da se vojaško neposredno ne angažira v Ukrajini in da v Ukrajino ne pošilja orožja, s katerimi bi slednja lahko napadla cilje v Rusiji. Denimo raketni sistem HIMARS ima doseg zgolj 300 kilometrov.

Dejstvo je tudi, da so ZDA – kljub močnemu povečanju vojaške in finančne podpore Ukrajini – močno ublažile retoriko glede ciljev v ukrajinski vojni. Ameriška retorika se je ublažila na tem, da si zdaj želi “demokratično, neodvisno, suvereno in uspešno Ukrajino“. Ne sprejema pa zahteve Ukrajine po vrnitvi vseh izgubljenih ozemelj, vključno z ozemlji, ki jih je Rusija zavzela leta 2014. V komentarju za New York Times je maja ameriški predsednik Biden naštel veliko stvari, ki jih ZDA ne bi naredile in ki so v prejšnjih komunikacijah bile postavljene zelo ostro ali dvoumno. ZDA si naj ne bi prizadevale odstaviti ruskega predsednika Putina. Ne bi poslale vojakov v Ukrajino ali se neposredno angažirale proti Rusiji. Ne bi spodbudile ali omogočile Ukrajini, da napade Rusijo. Prav tako naj ne bi “podaljševale vojne samo zato, da bi Rusiji zadal bolečino”.

Čeprav je, kot se zdi, prav slednje strategija ZDA. ZDA so očitno že “odpisale” že osvojene ruske in proruske regije (Krim, Doneck in Lugansk), danes pa prav toliko vojaško podpirajo Ukrajino, da slednja lahko vzdržuje status quo glede še neosvojenih regij na jugu Ukrajine (okrog Hersona), kjer rusko prebivalstvo ni prevladujoče, so pa področja strateško pomembna za Rusijo tako iz vidika kontrole nad obdelovalnimi površinami in kanali za izvoz žitaric kot iz pogajalskega vidika, ko bo do mirovnih pogajanj prišlo.

Politika ZDA očitno cilja na pat položaj, kar pomeni dolgo vojno oziroma evropski Afganistan v Ukrajini, s čimer bi ZDA postopno vojaško in ekonomsko izčrpale Rusijo. Toda ceno slednjega bi ob Rusiji seveda plačale predvsem evropske države, saj zanje to pomeni srednjeročno visoke ravni energentov, pomanjkanje energije, surovin in hrane ter izgubljen ruski trg. To za Evropo pomeni stagnacijo ob povišani inflaciji – stagflacijo. Čeprav so politična vodstva v Evropi morda celo pripravljena plačati to ceno, pa je vprašanje, kako dolgo so pripravljeni to tolerirati evropski volilci. Leto stagflacije še gre, toda ko bo zima pokazala svoje zobe in ko bo prihajalo do redukcij pri distribuciji plina in elektrike, se bo pripravljenost evropskih volilcev, da z zmrzovanjem in prek visokih položnic za elektriko in goriva plačujejo račun za ameriško vojno v Ukrajini, močno usula. Pričakujemo lahko porast nezadovoljstva, povečano politično nestabilnost in vzpon desnega populizma. Podobno kot lahko že spremljamo v Italiji.

Putin najbrž računa s slednjim, zato je zanj smiselno, da zapre plinovode proti zahodni Evropi. Putin mora svoje cilje doseči v roku največ enega leta, pet ali deset let angažmaja v Ukrajini pomeni zanj in za Rusijo absolutno katastrofo. Sankcije delujejo na dolgi rok, vendar temeljito. Državo predvsem tehnološko odrežejo od sveta (ni več ključnih sestavnih delov, ni več vzdrževanja obstoječe tehnologije v indstriji, letalstvu, ni povezav s svetovnimi omrežji, ni finančnih povezav, ni tehnološkega napredka). In Rusija ni Kitajska, ki je svojo tehnološko in industrijsko bazo izgradila povsem na novo in je zato praktično neodvisna od Zahoda. Rusija je res zgolj “bencinska črpalka z jedrskim orožjem” ter razvito jedrsko tehnologijo in nekaj računalniške inteligence.

Jedrska vojna v Evropi se torej za zdaj zdi manj verjetna, vendar je ni mogoče izključiti. Ena neprevidna gesta s strani ZDA, ki bi prizadela varnost Rusije, ali pa frustracije s strani Putina glede stanja v ukrajinski vojni, pa tudi denimo resnejši napad na Krim, ki je za Rusijo simbolnega eksistencialnega pomena, lahko privede do prenagljene nepovratne poteze.

(Toda ob vsem tem pa je žalostno, da se danes nihče več ne vprašuje, kakšno ceno bo za to podaljšano ameriško vojno v Ukrajini plačala Ukrajina. Slednja je praktično izgubila ruske in proruske regije, vojaško jih ne more dobiti nazaj brez izrazito povečanega ameriškega vojaškega posredovanja, česar pa slednje niso pripravljene narediti glede na grožnjo ruskega jedrskega odgovora. Ukrajina se danes bori le še za vzdrževanje pat pozicije v južnem delu, ki pa bo v primeru mirovnih pogajanj itak pristalo nazaj pod ukrajinsko kontrolo. V Ukrajini po nepotrebnem dnevno umirajo stotine mladih fantov, po nepotrebnem se dnevno uničujejo domovi in ključna infrastruktura. Kakšen smisel ima vztrajati pri tem do zadnjega za borbo sposobnega moža, do zadnje porušene vasi in zadnjega porušenega mostu, če pa je jasno, da so pozicije razdeljene in praktično priznane s strani glavnega sponzorja te vojne (to je ZDA)? Kakšen smisel ima vztrajati v statusu Afganistana? Ukrajini grozi, da bo končala enako kot Afganistan, Irak, Sirija, Libija, ki so jih kot poligon uporabile ZDA – porušena, brez perspektive in z eksodusom mlade generacije. Ameriški vladni administraciji je seveda za to vseeno, zanjo je Ukrajina le nov poligon za še eno izmed njenih interesnih vojn.)

Spodaj je nekaj razmišljanj različnih analitikov na temo možnosti nuklearne vojne iz The Economista.

On the day he invaded Ukraine Mr Putin threatened outsiders thinking of intervening with immediate consequences “such as you have never seen in your entire history”. State media in Russia fantasise luridly about nuclear strikes on the West. For now, though, America says there is no sign that Russia has put its nuclear forces on higher alert. America and Russia still swap information about their long-range nukes. On August 1st Mr Biden called on Russia to resume arms-control talks.

Over five months of fighting, the threshold for a direct clash has repeatedly shifted, seemingly without dire consequences for the West. “NATO has been brilliant at salami-slicing its assistance,” says James Acton of the Carnegie Endowment for International Peace, a think-tank in Washington. “It has given the Ukrainians a fair amount of support, but at no time did it present Russia with a point at which they could say, ‘No further’.”

Not all agree. “Every salami-slice means that more innocent Ukrainians are killed,” retorts Ben Hodges, a former head of American forces in Europe. He says the Biden administration “has overstated the risk of escalation.” The Kremlin, he argues, is already doing its worst, in terms of atrocities and of military effort, and its navy and air force are “terrified” of the Ukrainians. Russia does not want to take on NATO, says the ex-general, and a nuclear response is highly unlikely.

Others caution that Russia may escalate rather than accept defeat. Samuel Charap, of the RAND Corporation, a think-tank closely tied to the Pentagon, says Russia has unused military capacity, especially if it initiates a mobilisation. The air force could also be committed more fully. The more the West helps Ukraine, the more Russia will raise the stakes. “There is no stable equilibrium,” argues Mr Charap. “We are in a slow-moving, incremental escalation.”

Cold-war history suggests that countries can go a long way in waging proxy wars against nuclear powers without atomic retribution (albeit with scares). Think of Russia and China supporting North Vietnam against America in the 1970s; or America arming the Afghan mujahideen to bleed the Soviet Union in the 1980s.

Russia’s published doctrine envisages four scenarios for the use of nuclear weapons: detection of a ballistic-missile attack against Russia or its allies; an attack on them with nuclear or other weapons of mass destruction; actions that threaten its nuclear command-and-control systems; and “aggression against the Russian Federation with the use of conventional weapons when the very existence of the state is in jeopardy”.

On the face of it, the West’s arming of Ukraine falls well short of any of those red lines. Yet the concept of an existential threat is elastic, notes Bruno Tertrais of the Foundation for Strategic Research, a think-tank in France. Mr Putin has described Ukraine as “a matter of life and death”. He has also suggested that any attack on Crimea, which Russia annexed in 2014, would be similarly grave (and if Russia formally annexes more Ukrainian territory, trying to retake it may become more dangerous). Others ask, what if Mr Putin regards himself as the state, so that any danger to his regime is deemed an existential threat to Russia?

A recent RAND paper by Mr Charap and others sets out four scenarios of horizontal escalation. The first is labelled “Pathway 0” because the escalation spiral may already be under way: Russia is bound to respond to heavy military and economic losses inflicted on it, if not now then “in due course”. Next is a pre-emptive attack by Russia if it thinks NATO is about to intervene directly, after it deploys missile systems near the Russian border, say. Third is hitting military supply lines that support Ukraine. Last is “a dramatic increase in domestic, economic, and political instability in Russia”.

In most cases Russia’s retribution would probably begin covertly—eg, through cyberattacks, sabotage, assassination and more. The pre-emption scenario is most likely to provoke a military attack, perhaps even a nuclear strike. The scenarios may overlap and “all are more dangerous if Russia is losing”, Mr Charap adds.

In truth, nobody knows where Mr Putin’s red lines lie. Perhaps not even he does. America has stopped talking of helping Ukraine “win” and of weakening Russia. Instead it speaks of ensuring Ukraine does not lose. In an op-ed for the New York Times in May Mr Biden listed many things America would not do. It would not seek to unseat Mr Putin. It would not send troops to Ukraine or fight against Russia. It would not encourage or enable Ukraine to strike at Russia. Nor would it “prolong the war just to inflict pain on Russia”.

Mr Biden warned Russia that using nuclear weapons “would entail severe consequences”. A response would depend on the circumstances, but officials whisper it may involve conventional rather than nuclear strikes. Plainly, Mr Biden does not want to get to that point.

While steering around these self-imposed limits, Mr Biden has left his destination undeclared. Informed sources say senior officials are conducting wargames to decide on their ultimate objective. For now the administration speaks in bromides, saying it wants “a democratic, independent, sovereign and prosperous Ukraine”. It does not adopt Ukraine’s demand for the return of all lost territories, including land Russia took in 2014. Intentionally or not, Mr Biden’s policy is likely to generate a long war or a grinding stalemate. That risks cracking the unity and staying power of Western countries if voters revolt against stagflation, energy scarcity and the bill for supporting Ukraine. That may, of course, be Mr Putin’s plan.

Yet frustration and uncertainty is in the nature of nuclear dissuasion: America is deterred from intervening directly; Russia from striking at NATO. The late Tom Schelling, an economist and nuclear strategist, argued that the brink of war can be unknowable: it is not “the sharp edge of a cliff where one can stand firmly, look down, and decide whether or not to plunge”; instead it is a slippery curved slope where “neither the person standing there nor the onlookers can be quite sure quite how great the risk is”. When the peril is a catastrophic nuclear exchange, who can blame leaders for treading carefully?

Vir: The Economist