Peter Paret's Makers of Modern Strategy from Machiavelli to the Nuclear Age is a little dated (the most recent edition is from 1986!) but it is still oft-used as an intro textbook for military history and strategic studies programs. A good annotated copy of Clausewitz's Vom Kriege would probably serve you well, just because it's been so strikingly influential. Looking at the modern/postwar strategic world, major works in deterrence theory & nuclear strategy like Kahn's On Thermonuclear War or Freedman's The Evolution of Nuclear Strategy will serve you quite well. Hughes and Philpott's (eds.) 2006 Palgrave Advances in Modern Military History is a decent but not spectacular survey of, well, what it says on the tin. It has chapters surveying the 'New Military History'/war and society approaches of the 70s and onwards, newer understandings of conflict from antiquity through the early modern era, and a chapter on non-Western military history. Rob Citino's 2007 article in The American Historical Review "Military Histories New and Old: A Reintroduction" is a good summary too. These two are not that relevant to the strategic history interest you mention below, but I think I'd be incredibly remiss in not recommending some writings outside the strategic bubble.

On the Russian side, ho boy there is a lot. The Soviets really liked to write about war. The early stuff is pretty Jominian, though I think it picks up its own very distinct flavor after WW2. As a survey, David Glantz's Soviet Military Operational Art: In Pursuit of Deep Battle and The Military Strategy of the Soviet Union are (wow, never expected to say this) getting a little long in the tooth but are both fundamentally sound and will likely be reference books in the field for years to come (Glantz is still rightfully so the 'granddaddy' of good English language Soviet military study). For a deeper cut I think you'd be well served by starting with Jacob Kipp's annotated translation of Triandafillov's The Nature of the Operation of Modern Armies, as well as Bruce Menning's annotated translation of Isserson's The Evolution of Operational Art. Richard Harrison's Architect of Victory is a good biography of Isserson and it does a good job embedding his military theories within their historical context. I don't have a favorite translation of Svechin's Strategy, but it's absolutely foundational. There's a 2012 journal article by David Stone, "Misreading Svechin: Attrition, Annihilation, and Historicism" that you should also read. Mikhail Tukhachevsky's views, which emerged at the same time as Svechin's but followed a different path, are harder to pin down with a single book. Probably its treatment in In Pursuit of Deep Battle will suffice for starters, unless you decide that Soviet theory is your jam in which case please PM me or post in the Thursday reading-rec thread and we can hook you up with some more high-level readings. Getting deep in the weeds here will eventually require some Russian language skills. Moving into the modern era, less of it is translated. Jacob Kipp's translation of Makhmut Gareev's If War Comes Tomorrow? The Contours of Future Armed Conflict will bring you into the 80s, and somewhere around the internet are interviews that Marshal Nikolai Ogarkov did after the end of the Cold War, in which he discusses his own perceptions (as the Soviet Minister of Defense during the early 80s) of war with NATO.

Have you a particular element of military history you are especially interested in? I'm happy to recommend some more general readings, but most of those are more about the ethics and philosophy of warfare, and not necessarily the more fun or interesting case studies you'd find in descriptive histories of singular events and/or processes.