It sounded like an echo of Sino-Soviet alliance of the 1950s and 1960s when China’s new defense minister, Wei Fenghe, said at a meeting in Moscow this month, “The Chinese side has come to show Americans the close ties between the armed forces of China and Russia.” A full-blown military alliance remains a long ways off, of course, and it is easy to dismiss Wei’s remarks as rhetorical posturing. But that would be a mistake, because Wei nonetheless captured an ominous feature of world politics today: the growing alignments between America’s various geopolitical rivals. That alignment is not new, of course: Rogue states and American adversaries such as North Korea, Syria and Iran have cooperated on issues from arms sales to nuclear proliferation for years. What is changing now is that collaboration between America’s great-power competitors is increasing, as the threats to the US-led international order also grow. Start with Russia and China. As those countries have intensified efforts to reassert their geopolitical influence, they have made common cause on a number of fronts. China provided diplomatic cover for Russia in the United Nations Security Council after Moscow’s annexation of Crimea in 2014, despite its traditional reluctance to support “separatist” movements for fear of emboldening such forces on Taiwan. Moscow and Beijing have also worked together to block UN support for intervention against the Assad regime in Syria, and to oppose additional US military deployments on the Korean peninsula, while also pursuing closer bilateral ties with respect to arms sales, energy deals and development of military technology. Most visibly, the two countries have conducted combined naval exercises in the South China and Baltic Seas and in the Sea of Japan, areas in which Chinese and Russian tensions with Washington are particularly sharp. Altogether, cooperation between Moscow and Beijing is more significant than at any time since the Mao-Khrushchev split more than half a century ago. Nor is this the only pair of American antagonists currently cooperating. Russia and Iran have often been geopolitical rivals, but today they are working in tandem to undermine American influence in the Middle East. Tehran and Moscow have formed a de facto military alliance to keep Syrias Bashar al-Assad in power -- and thus preserve or increase their own sway in the region -- with the Russians providing the airpower and the Iranians (or the proxy militias they control) providing the shock troops. Coordination between Russian and Iranian officials has intensified not just on the battlefield but also at the top levels of government. “Our cooperation can isolate America,” Supreme Leader Ali Khamenei reportedly told Russian President Vladimir Putin in late 2017. And last month, Bloomberg reported that Iran’s Russian-provided SA-20C air defense system was now operational, giving Tehran what US intelligence officials have called a “generational improvement in capabilities.” These alliances are all the more noteworthy for the fact that America’s rivals are not, by any means, natural partners. Russia and China continue to compete for influence in Central Asia and elsewhere; the growth of Chinese power may ultimately pose as much of a threat to Russia -- a country with which it shares a long land border -- as it does to anyone else. One would also expect to see some inevitable tensions between Iran, which is bidding to become the dominant power within the Middle East, and Russia, which is increasingly throwing its weight around in the region. Yet if the cooperation between US rivals has rightly been described as more opportunistic than systematic, it is striking that these countries are finding more and more occasions when working together appears to be in their interests. This is happening for two reasons, one geopolitical and one ideological. The geopolitical reason is that what Iran, Russia and China have in common is that they are all trying to weaken, in their own way and for their own motives, an international order that is built on the dominance of the US, its allies and its partners. Given the inherent dangers and difficulties of taking on the leading power and its formidable strategic coalition, they are naturally attracted to cooperating with states that share their hostility to the US-led system and can help them nibble away at its edges. It may well be true that, over the long term, Russia has more to fear from a rising, aggressive China than it does from a democratic, declining Europe. Yet for the foreseeable future, the revisionist powers all share a common strategic adversary. The ideological reason is that these countries also share a commitment to illiberal rule in a relatively liberal age. Admittedly, we have not gone back to the 1950s, when the ideological conflict between Washington and Moscow took on global dimensions. Marxism-Leninism no longer provides the core of the relationship between Moscow and Beijing, as it did in the days of Stalin and Mao. But Russia, China and Iran are all autocratic regimes that see themselves fighting for influence and even survival in a world in which the leading power is a democracy and democratic values are still pre-eminent. Strategic and ideological resistance thus go hand-in-hand. Bloomberg