Russia and China are on the brink of a military alliance that could overwhelm the US

• For decades, the US has been the world's main military superpower.
• But the US faces formidable new threats, and rising global conflict.

For decades, the military might of the US was unchallenged.

After the collapse of the Soviet Union in 1991, the US was the world's only military superpower, with its forces deployed all over the world to defend allies and deter aggression.

But as 2023 draws to a close, conflicts are flaring across the world, and Russia and China are growing increasingly aggressive in their shared ambition to topple the US as the world's biggest power.

Their authoritarian leaders, Xi Jinping of China and Vladimir Putin of Russia, are seeking to exploit global instability to damage the US and its allies, say analysts, and are drawing closer to forming a military alliance that poses the biggest threat the US has faced in decades.

"It is clear that the two states see themselves as military partners, and that this partnership is growing deeper and more experienced, even if it is not a formal alliance in the Western sense," Jonathan Ward, CEO of the Atlas Group, told Business Insider.

Xi and Putin draw closer to formidable military alliance

In conflicts across the world, the rivalry between the US and the Russian and Chinese partnership is playing out.

China has provided Russia with vital economic and diplomatic support in its unprovoked invasion of Ukraine, while the US has provided billions in aid to Kyiv.

In the Middle East, Russia and China have aligned themselves with Iran and criticized Israel's attacks on Gaza to destroy the Tehran-backed terror group Hamas. The US, meanwhile, has provided military aid and diplomatic support for Israel.

China, say experts, is likely watching the outcome of the Ukraine war carefully for signs of how the world will react should it act on plans to seize control of Taiwan.

And as they draw closer, China and Russia are increasingly coordinating their military resources.

"The Russia-China 'comprehensive strategic partnership of coordination for a new era' has always been about military power," said Ward.

Over the past two years, Russia and China have launched joint naval exercises in the Sea of Japan, Russia has handed China submarine technology that could give it the edge in a war with US allies in the Pacific, and the leaders have pledged to cooperate on high tech weapons development, Putin said in November.

Russia has also sold China Su-25 jets, MI-17 helicopters, and S-400 air defense systems.

Though the leaders have not signed a formal military alliance, such moves should be of huge concern to the US and its allies, writes Chels Michta in a recent article for the Center for European Policy Analysis.

"A full-scale China-Russia alliance would present the United States with a threat unlike any it has confronted since the end of the Cold War," writes Michta.

US military urged to address new threat

During the Cold War, the Pentagon planned to be able to fight one major war and two smaller wars simultaneously. But in the face of changing threats, it shifted its strategy to be able to fight one major war and deter other attacks.

The Congressional Commission on the Strategic Posture of the United States in October said that the US now faces threats "fundamentally different [to] anything experienced in the past, even in the darkest days of the Cold War" because of the rise of China and Russia.

It urged the Pentagon to revise its plans to be ready for the possibility of war with China and Russia simultaneously.

"The Russia-China axis poses an enormous threat to the United States given that we will have to handle security in both Europe and Asia, as well as in the Middle East, with the risk of being stretched thin while Beijing and Moscow coordinate to pursue their respective regional ambitions," said Ward.

Some experts remain skeptical of the stability of a Russian-Chinese alliance, pointing to long-standing tensions between the powers, and China's desire to retain strong ties to lucrative Western markets.

But the possibility of a military pact between the authoritarian leaders is one which experts say the US has to ready itself for.

The US' global alliances are hugely important for its capacity to offset the threat posed by the rival superpowers. Particularly in Europe, they have to urgently step up and boost their military capacity, said Ward.

"The United States can still handle both threats, but this will require substantial increases in burden sharing, especially among European allies who have now seen the true consequences of Russia-China geopolitical 'coordination' since the invasion of Ukraine," said Ward.