Why are Russia and Ukraine at war — and why has the war been so difficult to end?

The country’s geography creates both opportunities and exposure. Odesa and other ports connect Ukraine to world grain markets; the Dnipro and southern steppe shape transport and farming; and the flat terrain allows large armies to move but offers little natural cover. Crimea’s location beside the Black Sea and Sevastopol gives whoever controls it a naval base and leverage over shipping.

The immediate chain is specific to Why are Russia and Ukraine at war — and why has the war been so difficult to end? : The war grew from the collision of Ukrainian sovereignty and political choices with Russian security claims, territorial ambitions and ideas about Ukraine’s place in history and Europe. NATO expansion matters, but it is not a complete explanation. Since 2014, Crimea and the Donbas created unresolved territorial and security disputes. The 2022 invasion widened them into a full-scale war sustained by Ukrainian resistance, Russian mobilisation and production, and outside military, financial and diplomatic support. Peace is difficult because territory, security guarantees, alliances, sanctions, justice, displaced people and reconstruction are linked. Stopping fire does not automatically settle what comes next.

The system is constrained by the conditions described in the story. The war has several layers: the breakup of the Soviet Union, Ukrainian domestic politics, Crimea and the Donbas, NATO and Russia’s security arguments, national identity, military capacity and the involvement of outside powers. No single layer explains the whole conflict. The outcome depends on which pressures are strongest, which resources are available and how the people or institutions involved respond.

The situation can change when the relevant actors alter their behaviour, when a key resource becomes scarce or available, or when a rule changes who can act and at what cost.

The consequences extend beyond the immediate question. The war matters because it determines the safety and political future of millions of Ukrainians while testing rules about sovereignty, borders and security in Europe. Its effects reach energy bills, grain prices, defence budgets, migration and relations among major powers. European security → Russia’s invasion has pushed NATO members to revise defence plans, increase spending and expand weapons production, while neighbouring states host troops and refugees. Energy → Russian oil and gas sales provide revenue; European diversification, sanctions and shipping routes alter prices and the money available to each side. Food → Ukraine and Russia are major agricultural exporters. Black Sea attacks, mines and shipping agreements can change grain availability and prices in countries far from Europe. Defence industry → Demand for shells, missiles, drones and air-defence interceptors is exposing production bottlenecks and reshaping procurement in Europe and the United States. US–Europe relations → Ukraine’s ability to resist depends partly on American intelligence and weapons and European finance and industry, making domestic politics in both places relevant to the battlefield. Russia–China relationship → Chinese trade and dual-use components can help Russia adapt to Western restrictions, while Beijing weighs its relationship with Moscow against trade with Europe and the United States. Global diplomacy → Governments outside Europe assess the war through food, energy, sovereignty and Western power, which affects sanctions, negotiations and the legitimacy of different peace proposals.

The balance: Russia’s ability to continue depends on manpower, weapons production, energy revenue, outside suppliers and domestic political capacity, offset by losses and constraints. Ukraine’s ability to resist depends on its people, domestic production, Western weapons, air defence, finance and intelligence, offset by casualties, damage and uncertainty about support. What changes it: Recruitment, ammunition output, drone innovation, air defence, sanctions, economic resilience, Russian production and diplomatic movement can change the relative capacity of the two sides. Each variable works through real decisions by governments, factories, soldiers and voters. Why peace is hard: A settlement must connect territory with security guarantees, alliances, military limits, sanctions, justice, prisoners, displaced people and reconstruction. A proposal that reassures one side can leave the other exposed or politically unable to accept it.