The US-Israeli war with Iran has done much more than destabilize the Middle East, trigger a surge in energy and other prices, and disrupt the global economy. It has also left US allies and rivals scrambling to respond to an unpredictable and unreliable superpower. The result is an historic geopolitical realignment that will shift the global balance of power over the next decade.

Of course, the war's effects are most immediate and profound in the region where it is being fought. It has already helped persuade many Gulf Arab states that the Gulf Cooperation Council-a loose diplomatic, economic, and security arrangement long plagued by infighting-is no longer fit for purpose.

The war also intensifies the rivalry between Saudi Arabia and the United Arab Emirates, which recently announced its intent to end its nearly six-decade membership in OPEC. The UAE will now align more closely with Israel on intelligence, technology, and security, in hopes of crippling the Iranian regime. Saudi Arabia, by contrast, will try to find ways to live peacefully alongside the Islamic Republic by pursuing tighter military alignment with nuclear-armed Pakistan, as well as with Egypt and Turkey, and closer coordination with China.

Both these blocs will also try to keep their close security ties with the United States; but that will no longer be as easy as it once was. One of the most immediate and striking effects of the war is that it has eroded the foundation for coordinated decision-making across the Middle East.

Then there is the flagging transatlantic relationship. At a time when Russia's war on Ukraine is fueling anxieties across Europe, the Trump administration's decision to focus on Iran-and then to lash out at European leaders for not helping-generates new momentum toward a European collective-defense arrangement outside NATO.

True, President Donald Trump is unlikely to try to withdraw the US from the transatlantic alliance, and the US Senate could legally block such a step. But his May 1 announcement that the US would withdraw 5,000 of its 36,000 troops stationed in Germany, coming just a few days after German Chancellor Friedrich Merz criticized the war, has caused further alarm across the continent. Trump has also ignored European objections to the suspension of some sanctions against Russia.

The result is a deeper fragmentation within the Western alliance, and growing European fears that the White House may eventually push for a US-Russia security understanding. That prospect gives Russian President Vladimir Putin reason enough to continue his war in Ukraine, in the hope that Russia can eventually break through as NATO breaks down.

Across Asia, the effective closure of the Strait of Hormuz is inflicting a heavy economic cost. Like America's historical partners in Europe, its Asian allies are feeling insecure about the Trump administration's longer-term security and economic commitments. But countries like Japan, South Korea, and Taiwan have fewer alternatives than do Germany, France, and Britain. There is no Asian NATO to tie them to Washington, nor any EU-like institution to bind them to one another.

Moreover, they all face pressures created by China's economic, technological, and (growing) military power. China is now acting more assertively toward Taiwan's ruling party and Japan's government. These and other factors substantially limit the possibility that America's Asian allies can follow the Europeans toward greater independence from the US.

As for China itself, Chinese President Xi Jinping, aware that the economy is slowing, and that the adventurism of Trump and Putin has done them and their countries no favors, has refrained from using America's moment of distraction to take on new risks. Instead, he is likely to lavish Trump with pomp and circumstance when Trump visits Beijing this month, seeking an explicit US disavowal of Taiwanese independence claims. In return, Xi might pledge sizable Chinese commitments to purchase US goods. Even Trump's closest advisers cannot be sure that he would resist that temptation. Needless to say, US allies in Asia and elsewhere will be watching closely.

The Iran war has also accelerated another important shift involving China. It has shown Iran's leaders and the world just how easy and inexpensive it is to close the strategically vital Strait of Hormuz to oil and gas trade. Other bottlenecks, like the Bab al-Mandab, which separates Yemen from Africa, and even the Strait of Malacca in Southeast Asia, are all potentially in play. Moreover, this comes at a time when China is the undisputed global leader in sustainable energy, electric vehicles, and batteries, and the critical minerals and reprocessing that support them.

China's own historic shift toward post-carbon energy production makes it a far more appealing commercial partner for the world's major energy importers. Everyone needs more energy, and while that confers near-term benefits on the US (and the dollar) as the world's largest hydrocarbon producer, the vulnerabilities exposed by the war create enormous longer-term opportunities for China.

For all these reasons, the still-raging Middle East conflict will do more to shift international partnerships and the global balance of power than any event since the end of the Cold War.

From Project Syndicate