Which important city did Russia threaten to take after the Russo-Turkish War?

The correct answer is Istanbul. Following the Russo-Turkish War, which began in 1877, Russia sought to expand its influence and control in the region, particularly in the Balkans and the Ottoman Empire. Istanbul, historically significant as the capital of the Ottoman Empire and a strategic hub connecting Europe and Asia, was a focal point of Russian ambitions. The war ultimately aimed to liberate Slavic peoples under Ottoman rule and gain territory, with Istanbul representing a quintessential target for Russian expansion.

In this context, the city's geographical and political significance made it a prime objective for Russia after their military successes in the conflict. Other cities mentioned, such as Thessaloniki, Alexandria, and Cairo, though important in their own right, did not hold the same level of strategic importance in relation to Russian aspirations at the conclusion of the war. Thus, Istanbul stands out as the most relevant and threatening target in Russia's post-war strategies.