Geopolitical thinkers like Alfred Mahan and Nicholas Spykman in the late 19th and early 20th centuries feared that if a country or group of countries managed to conquer all or most of Eurasia, they would wield more power than any other countervailing alliance and could use Eurasia as a platform to build navies and project power across the oceans, threatening even distant countries.

What Russia, China, Iran, and North Korea are each individually trying to do is upset the balance of power in key regions (Eastern Europe, Middle East, East Asia), but collectively they are trying to shift the balance of power in all of the key regions that make up Eurasia and undermine the rules and norms that the U.S. and its friends established to contain Eurasian anarchy after 1945.

There are questions about what specifically tactically would precipitate a Chinese move against Taiwan, and the outcome in Ukraine will not be the dominant factor, but it will be a factor in influencing Xi Jinping's anticipation of how the West would react if he attacked Taiwan.

Eurasia encompasses the combined expanse of Europe and Asia from the Atlantic coast of Europe to Asia's Pacific margins, including nearby offshore islands like the United Kingdom, Japan, and the Philippines, and contains most of the world's people, economic resources, and military potential.

Russian military dealings and military co-production with China has already accelerated China's military buildup in some important ways, and the fear is that as Russia becomes more dependent on these relationships it will increasingly trade away its technological crown jewels—marine quieting technology, space launch technology, and other forms of knowhow—to China and North Korea in ways that accelerate the emergence of disruptive military challenges in other regions.

Putin is willing to take a hard bargain with China (involving Chinese economic and technological penetration of Russia) because he believes it increases his chances of prevailing in Ukraine and strengthening Russia against the West over the medium term.

Americans and Europeans are 'prisoners of their experiences' since 1949 with NATO and have developed a bad habit of assuming that NATO—which is a permanent, values-based alliance—is how all alliances work, when in fact NATO is much more the exception than the norm; most alliances in history were temporary and tactical, and most are 'marriages of convenience' that do not require permanent affection.

Nobody around Xi Jinping believes there is a fundamental reset of Sino-American relations coming, so if high tensions and strategic confrontation with the United States are expected in the coming years, China must keep its relationship with Russia in good shape and continue to deepen it, and if China finds itself in a deeper crisis or war with the U.S., it will need at minimum benign Russian neutrality and ideally active Russian support.

Just because the United States decides that the primary threat is in one theater does not mean that problems in other theaters go away—the U.S. has faced this challenge since the late 1930s of figuring out how to execute a global foreign policy even as one region may seem more important than others, and this was evidenced by FDR's willingness to accept high risk of war with Japan before getting into war with Germany despite believing Germany was the bigger problem.

The 'Asia First' policy argument that the U.S. should focus entirely on China and let Europe handle Russia has intellectual appeal but suffers from serious liabilities: even if European NATO members doubled military spending, it wouldn't solve how to sustain Ukraine for 3-4 years because European defense industrial bases cannot do that, and it wouldn't address Russia's hyperactive revisionism and risky sabotage/subversion efforts within the West.

The U.S. role in Europe is uniquely trusted precisely because it is not European and is not part of Europe's old system of rivalries—this external role was the key solution after WWII to both deter Soviet aggression and tamp down intra-European tensions that had ripped Europe apart twice in the quarter-century before 1939, and if the U.S. withdrew from NATO, you could see an erosion of these arrangements and a return to more rivalrous Europe.

The stakes of the Ukraine war are not limited to Ukraine and Europe but are much more a global contest about the future of the international order and the norms that govern it.

Without Chinese economic aid, economic support, and trade that has sustained Russia's war economy over the past three years, along with military equipment and troops from Iran and especially North Korea, Putin would have lost the war in Ukraine by now, demonstrating that this autocratic cooperation is shifting the strategic equilibrium in concrete ways.

You don't have to believe that the autocratic coalition will hold together permanently to see that it is already having pronounced strategic implications right now.

Typically what happens is that it takes a crisis of some sort to accelerate the formation of relationships and overcome barriers to collective action, and Ukraine has provided that crisis for the autocratic coalition, causing Russia to quadruple down on its ties with other revisionist powers as a response to economic sanctions and diplomatic isolation from the West.

Autocrats know Cold War history as well as the West does, they know the United States will be looking for opportunities to split them, and they are on guard against this, making it tough to execute a wedge strategy.

There might be one or two opportunities to start a very long process of straining autocratic relationships over time, particularly by putting pressure on the weakest member of the quartet, Iran, which has had its air defenses shredded and its proxy network set back dramatically, and the Trump Administration is likely to come out of the gate with sharp economic pressure on Iran to deal with the Iranian nuclear program.

The completion of the Trans-Siberian Railway and proliferation of railways across Eurasia in the early 20th century created new possibilities for large-scale military conquest by enabling big aggressive powers to move armies over larger distances than previously possible since Genghis Khan.

Technology is not static; its evolution changes the particulars of the struggle for Eurasia (carrier-based air power in WWII, nuclear weapons in the Cold War, anti-ship missiles and cyber/AI in the 21st century) even as the underlying geographic pattern remains constant.

The nature of economic power has not changed as fundamentally in the 21st century as some believed 10-15 years ago; the ability to manufacture goods remains really important, not just occupying key nodes in value chains and dominating high-tech industries.