China’s and Russia’s leaders announced a range of new deals on the eve of Russia’s seventieth celebration of its victory in the Second World War on Friday. This increased cooperation between the two powers hardly amounts to a new alliance but American strategists should nonetheless start thinking about how to avoid such an alliance from coming about.

America’s overriding strategic goal must be to prevent any one power or bloc from dominating the Eurasian landmass. The United States are secure in the Western Hemisphere; only a united Eurasia can produce a rival to what is still the world’s superpower.

This imperative compelled America’s involvement in World War II, when Germany and Japan threatened to split up the largest continent between them, and informed its policy of containment during the Cold War, when communist regimes were driving free and liberal states into the sea.

The specter of a Sino-Russian condominium should therefore be taken seriously. Both are authoritarian powers that want world order to shift away from American domination and toward — they say — multipolarity.

But Russia is more interested in deepening relations with China than the other way around. Its aggression in Ukraine — where it annexed the Crimean Peninsula and supports a separatist uprising in the Donbas — has alarmed the West, leading to a severing of ties. The European Union is fighting the dominant position Gazprom has on its natural gas market, Russia’s main instrument of leverage. The United States are expanding military support for new NATO member states on Russia’s periphery. It needs closer economic as well as strategic relations with China to offset this.

Hence the ratification of a thirty-year gas deal, estimated to be worth up to $400 billion, last year after more than a decade of negotiations. Hence also the signing of dozens more bilateral agreements on Friday, including a nonaggression pledge in cyber warfare. And hence the joint naval exercises China and Russia are staging in the Mediterranean Sea this week. This is all meant to demonstrate to the world that Russia isn’t isolated.

China’s own relations with the United States, however, are not veering off course. Late last year, after the Sino-Russian gas deal was finalized, America and China signed a number of key agreements: one on climate change, another on reducing technology tariffs and a third on averting clashes between their warplanes and -ships in the East and South China Seas. On themselves, the agreements weren’t hugely significant. But put together and given their timing, they made clear China is less interested in challenging the American-led world order than Russia is — at least for now.

It would seem to make little sense for China to its upset relations with the United States when its economy — and by extension, Communist Party rule — is dependent on transpacific trade. China is America’s second largest commercial partner, after Canada. America is China’s largest trading partner. The volume of trade between the two accounts for more than half a trillion dollars per year. Sino-Russian trade is less than a fifth of that.

Moreover, China and Russia compete for influence in Central Asia and could end up competing in Mongolia and the Far East, areas that possess natural resources China desperately needs to keep improving the livelihoods of its 1.3 billion people.

This assumes, however, that the West doesn’t imprudently push China and Russia closer together. If the United States are unable to accommodate a rising China that naturally expects a greater influence in East Asia or — worse — if China gets the impression that America intends to block its ascendancy, it could decide that the benefits of an alliance with Russia outweigh the costs and risks after all.