I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones.
There are two practical, interests-based possible negotiated arrangements to the Ukrainian Civil War.
Russia agrees to progressive sequential military withdrawal from Ukrainian territory in exchange for progressive genuine federalisation of the country's political system, including removal of the Ukrainian President who is profoundly unsatisfactory to Moscow and the total elimination of Ukraine's final politically surviving oligarch and the Ukrainian President's political and financial backer, Igor Kolomoisky.
Ukraine is partitioned along the final military line of control once a ceasefire is agreed, at best into two confederal entities that for the sake of placeholders we might call 'Free Ukraine' and 'Novorossiya'.
All civil conflicts that reach negotiated conclusions (as opposed to abject defeat by one side) fall into approximately one of these two categories. We might call this an iron rule of civil conflict.
However this civil conflict will not end in one of those two outcomes. The first reason is because nobody in the Ukrainian government is prepared to accede to a state-building regime for Ukraine the terms of which are negotiated with Russia, no matter how much Ukraine may need such a solution. There are also enforcement and observance problems: Russia, as by far the superior military power, will retain (as she did under the Minsk agreements ending the 2014 Russia-Ukraine conflict) the de facto unilateral right to determine whether whether Ukraine is complying sufficiently with her federalisation commitments.
Undoubtedly Ukraine will not do so; hence Russia may not withdraw; instead she may proceed yet further. In other words this option 1 is a choice to defer the war pending further military build-ups on both sides, not to end it, just as were the Minsk agreements ending the 2014 Russia-Ukraine conflict. So federalisation will not work, by reason of the outsized capacity of one of the parties that renders the concept of a neutral arbiter wielding overwhelming force impossible to insert into the situation.
Option 2 is a traditional nineteenth century balance-of-power approach to armistice. Such agreements no longer seem to work, because the overwhelming military power of the various Superpowers, which are still basically the Treaty of San Francisco 1945 members of of the UN Security Council, continues to include in sufficient quantities for each Superpower sufficient thermonuclear force to wipe their respective protagonists off the face of the map.
Any Superpower with such a capacity will never commit formally to a humiliating 'balance of conventional powers' climb down sufficient to create a stable armistice through partition. The situation is much like the 1953 armistice in the Korean War. The antagonists' proxies had so much obliterative force at their potential that they had no need to climb down. Nobody with thermonuclear intercontinental ballistic missiles and all the rest is obliged to climb down against anybody. Hence what you do is you reach a final front line partition based armistice after everyone has tired themselves out, but no peace agreement is ever concluded. We might call this option 2b.
The net result of option 2b whenever it is executed is permanent Cold War, as on the Korean peninsula. We used to know about Cold War in the West, until we decided to sideline all our experts after the end of the First Cold War in 1990. But to recapitulate, the essential features of Cold War are:
A non-agreed but de facto suffered partition of adjacent regions each dominated by a rival Superpower backer.
Constant paranoia that the line of partition will be breached by conventional or nuclear forces or spies or intelligence agencies.
Periodic accidental or intentional breaches of the line of partition by both sides, often to test the other side's military defences and determination.
An arms race, as each Superpower seeks to achieve parity with or dominance over the other Superpower. In the Second Cold War, the West will pour huge amounts of money into hypersonic ballistic missiles, for example, an area in which it has become quietly apparent that Russian technological advances have been steadily outstripping Western capacities. So the West will have to build some even faster, bigger ballistic missiles, and in larger quantities. To which the Russians will respond. And so on and so forth.
Various more or less pointless deterrence-based troop build-ups along contested borders, each imagined to deter a non-existent opposing ground invasion.
Reorientation of both sides' consumer economies towards military production.
Intermittent nuclear or other crises, as one side tests the other and misjudges their likely reaction (see e.g. the Cuban Missile Crisis 1962).
A massive increase in the espionage profession on all sides. Mystery, intrigue and glamour as a result.
Ongoing economic and political autarky between the adversarial sides.
Lots of proxy wars in parts of the world irrelevant to the principal dispute at issue, as the sides spin various theories such as 'the Domino Effect': your enemy's enemy must be your friend, or you risk losing another territory to the imagined ideological evil on the other side.
Suppression of civil liberties to restrict those who have nonconforming ideologies or views (e.g. the House Committee on un-American Activities and McCarthyism - the Soviets had lots of versions of this).
Media blackouts on each side against opposing information narratives.
Eventually, decades later, one or the other side cracks because they can't afford it. But this can take 50 years (as did the last one).
We will conclude this article with some final remarks.
The Second Cold War will roll back international free trade, thought by consensus to have kept the peace and promoted economic growth across the world since the signing of the GATT in 1945.
The theory propounded by John Maynard Keynes of the GATT was that countries that trade with each other go to war less -hence you abolish governmental barriers to their doing so. In the EU partial embargo on Russian oil supplies agreed between the EU member states agreed in the early hours of this morning 31 May 2022, all the progress in defusing Cold Wars between Superpowers (of which the EU is not one because Germany, the EU's principal economic powerhouse, has no nuclear weapons) embodied in the GATT and its successor the WTO has been undone.
A new series of European neutral / buffer countries - such as Hungary, Serbia and Turkey - will become centres of intrigue and conspiracy as they are used by the parties, now not communicating with one-another at all, to become centres of inter-agency intelligence communications.
This war has shown so far that air superiority is no longer nearly as valuable as it once was, because contemporary missile technology is so accurate against aircraft. It is remarkable that the biggest European war since World War II is not being fought with aircraft. That is because contemporary ballistic missile technology has advanced so much.
The same is true ergo for aircraft carriers, and hence for naval fleets more generally.
Hence we are returning to land-based warfare as predominant in non-asymmetric battlefield scenarios. So we watch the Ukrainians and Russians dig trenches that are then shelled, much like in World War I.
Value for money is important, as are long-term supply logistics. Hence we are seeing the return of high-accuracy mass shelling. The Russians can produce Krasnopol artillery pieces cheaply and quickly; and provided they are within 25km of a city centre, they are every bit as devastating as are contemporary cruise missiles. Moreover it does not matter if artillery pieces get blown up by expensive cruise missiles; they can be replaced with backups quicker and far more cheaply than cruise missiles can be produced. Krasnopol shells have inertial guidance mechanisms (making them very accurate) and are capable of hitting targets travelling at up to 36kph. They also have a double-fire capacity (meaning that one shell can be immediately followed by another using the inertial guidance system data provided by the first shell). By contrast, France, Sweden and other countries have developed even more accurate, longer range artillery pieces but at vastly greater cost and time to production. Hence it is a much bigger problem if they are destroyed in theatre. Mass armour that is tolerably accurate is now more important than small elite groups of armour that are highly accurate.
Sentry guns and other supposedly automatic armour defence systems have turned out in actual combat remarkably easy to get around - see e.g. the sinking of the Russian destroyer the Moskva. Her three-level system of sophisticated sentry guns was defeated by a group of cheap drones and hence she was sunk by a subsonic cruise missile. If that can happen to the Moskva, if can happen to any aircraft carrier. The myth of aircraft carriers' invincibility is suddenly swept away.
Tanks turn out now to be of limited value even on flat terrain, because they cannot be defended against tactical ballistic missiles. They are useful only in the final stages of taking a city, i.e. after it has been flattened by shelling and tanks then roll in and shoot anything still moving (see e.g. Mariupol and Severodonetsk, the latter taken yesterday 30 May).
Sanctions don't work against large economies, who will just trade with someone else, causing what economists call 'trade diversion' that economics predicts will increase the global price of the sanctioned commodity. (Freight rates in merchant shipping have been at historic lows for years for a variety of reasons outside the scope of this article, which makes the relative effect of sanctions on driving up prices of the sanctioned commodity all the greater.)
China will be watching carefully, as she learns the lessons of what is going on in Europe. China is a patient observer. Her continued apparently cosy relationship with the Russian Federation cannot be taken for granted, just as Detente in the 1970's split the Soviet Union and China. There is still everything to play for in a tri-headed geopolitical model (which is what it appears we now have).
In this new era of the Second Cold War, the world is about to change dramatically. In the interim, we have virtually learned by accident that the nature of modern warfare has dramatically changed as well.