No less an authority than Vladimir Putin has predicted that the coming years in global affairs will be a “revolutionary situation”: a reference to a line of Vladimir Lenin’s from 1913, just prior to World War I. Putin’s counterpart Xi Jinping concurs, foreseeing “changes the likes of which we haven’t seen for 100 years.”

This doesn’t mean World War III is inevitable or even likely. But it does mean we are in an era when the decisions of major leaders in moments of crisis could have an outsize impact on global security and the lives of millions.

This also is the moment when Donald Trump may return to the presidency.

The year 2016, when Trump was elected the first — and so far only — time, didn’t exactly feel like a very peaceful or stable moment in world history. The Syrian civil war and the US-led campaign against ISIS were raging. In June, one of the terror group’s sympathizers killed 49 people at a gay nightclub in Orlando. Russian-backed forces were occupying much of Eastern Ukraine and shot down a Malaysian airliner.

About a month before the election, North Korea conducted its most powerful nuclear test to date. Europe was still in the midst of an unprecedented influx of migrants from the Middle East and Africa, which would end up having dramatic political consequences in several countries. Ted Cruz was terrifying 3-year-olds on the campaign trail by telling them the world was “on fire.”

And yet, viewed from the vantage point of this year, 2016 feels like a simpler time. Wars of all types have gotten more common and deadlier around the world in the years since, and superpower conflict — a concern that had largely receded in the post-Cold War era — is back on the agenda.

In short, the global situation Trump would inherit if he were elected this time around would be far more dangerous and unpredictable. And that in turn raises the risks of his erratic and transactional approach to foreign policy.

What was, eight years ago, a localized “gray zone” conflict in Eastern Ukraine is now the first major land war in Europe in decades, one in which Russia’s president has repeatedly threatened to use nuclear weapons. Israel’s war in Gaza, already one of the deadliest conflicts for civilians of the 20th century, is fast spiraling into a regional conflict that could involve direct combat between Israel and Iran and could yet drag in the US military.

Further east, potentially even more dangerous conflicts loom. Many North Korea watchers believe the country is preparing for war, and that the risk of all-out conflict on the Korean peninsula — which could potentially kill more than a million people, even if North Korea doesn’t use its nuclear arsenal — has never been higher.

Then there’s Taiwan. Even putting aside a death toll on both sides that could dwarf the war in Ukraine, a war in Taiwan would be a body blow to the global economy. If the US came to Taiwan’s aid, it could lose as many troops in a matter of weeks as it did in 20 years of fighting in Iraq and Afghanistan. Some analysts believe China could even preemptively attack US bases in the Pacific if it believed US intervention was inevitable, something the US military has not experienced since WWII. And the threat of nuclear weapons use would loom over the conflict: China has the world’s third-largest nuclear arsenal, one that is growing fast.

China, Russia, North Korea, and Iran — a group some have dubbed the “axis of upheaval” — may not have much in common in terms of ideology of overall interests, but are increasingly collaborating: The reported presence of North Korean troops fighting alongside Russian forces in Ukraine is just the latest example.

None of this is to downplay the wars and security threats that existed in 2016 and continued through Trump’s presidency, nor the obviously massive disruptive effect of the Covid pandemic. But state vs. state conflict, and even superpower vs. superpower conflict, is an entirely different matter than war against terrorist groups. Gray zone conflict is a different matter than open warfare. Recent rapid advances in drone technology and artificial intelligence are likely to make the wars of the future all the more unpredictable, and potentially more destructive.

All of which makes the idea of putting back in the Oval Office a president who proudly calls his foreign policy approach “crazy” so dangerous.

Even putting aside the issues of Trump’s temperament, mental acuity, or the warnings from multiple senior national security officials from his own past administration that they believe he is dangerously unqualified for the presidency, there are several reasons to believe that a new Trump presidency would amplify this “revolutionary situation” rather than moderate it.

First, Trump does not put much value in the idea of territorial integrity. It may sound like a wonky academic point, but we tend to take for granted that in our current era, countries rarely conquer each other and borders are rarely changed by force. Russia’s invasion of Ukraine has obviously challenged this taboo against what the UN Charter calls the “threat or use of force against the territorial integrity” of other countries.

As president, Trump reportedly told other world leaders that the Crimean peninsula, which was illegally annexed from Ukraine in 2014, is rightfully Russian because everyone there speaks Russian. Figures close to the Trump campaign like Tucker Carlson and Elon Musk have openly endorsed the view that Crimea is rightfully Russian.

Trump overturned decades of US policy and international consensus by recognizing Israeli sovereignty over the Golan Heights, which he has described as a snap decision made after a quick history lesson from his ambassador to Israel and his son-in-law Jared Kushner. He did the same for Morocco’s claims over the disputed region of Western Sahara, in return for Morocco recognizing Israel. (In fairness, the Biden administration hasn’t reversed either of these moves — once the taboo is broken, it’s hard to reestablish.) For Trump, the president who after all, mused about buying Greenland, sovereignty and territorial integrity are like anything else in a deal: negotiable.

Second, Trump doesn’t value alliances. One reason why Russia has not attacked any of the countries bordering Ukraine, even as weapons flow into Ukraine from those countries, is that they are members of NATO, meaning that an attack on them could bring a military response from the alliance as a whole. It’s proof of concept for the most powerful military alliance in history.

Trump tends to take a narrowly transactional view of alliances. His antipathy to NATO and threats to pull the US out of the alliance have been well-documented, as have his comments that treat the US defense of Asian partners like Japan, South Korea, and Taiwan as a protection racket.

The third related point is Trump’s attitude toward nuclear weapons. Defying many predictions made at the dawn of the nuclear age, no nuclear weapon has been used in war since 1945, a record that likely involves both a bit of luck as well as the power of nuclear deterrence and the very justified fear these weapons cause. Trump, though, seems a bit more blase on the topic.

According to former aides, Trump discussed using a nuclear weapon against North Korea as president during the period he was publicly threatening Kim Jong Un’s regime with “fire and fury.” As president, he withdrew, or let lapse a number of key arms control treaties, most famously the Iran nuclear deal, instead preferring an approach where the US would build up its own nuclear arsenal to spend its rivals into oblivion. Recently on the campaign trail, he suggested that a reason presidents need legal immunity is so they could use nuclear weapons without fear of legal repercussions.

The issue is not just Trump’s own attitude toward nuclear weapons. In a number of US allies in Europe and Asia, there is now an active debate over whether they need nuclear deterrents of their own, driven in part by concerns over whether they could actually count on the US nuclear umbrella. Even Ukrainian President Volodymyr Zelenskyy recently suggested that without effective security guarantees from allies, his country might need nuclear weapons for protection.

The international community’s success at limiting the number of nuclear powers is one of the biggest reasons why the nuclear taboo has remained intact. But a world with more nuclear powers is a world where the use of nuclear weapons is more likely, and that world becomes more likely if allies don’t believe security guarantees are worth the paper they’re printed on.

An agent of chaos in the Oval Office

Trump would no doubt counter that the very fact that the world has become so dangerous is the reason he should be returned to the presidency. He has repeatedly made the unprovable claims that Russia’s invasion of Ukraine and Hamas’s October 7 attacks would not have happened had he been president. He has also falsely claimed that there were no terrorist attacks and no wars during his presidency. Those claims elide the major military escalations in Iraq, Syria, and Somalia that took place under his tenure, as well as risky actions like the assassination of Iranian general Qassem Soleimani, which prompted an Iranian missile strike on US troops in Iraq. Thankfully, no one was killed in those strikes, but commanders say up to 150 troops could have been. As president, he reportedly considered missile strikes into Mexico and the idea of sending troops into America’s neighbor — and No. 1 trading partner — has evolved into a mainstream Republican position.

The Trump case, essentially, is that he was able to rule the world through fear. In his debate with Vice President Kamala Harris, he cited his ideological ally Hungarian Prime Minister Viktor Orbán: “Why is the whole world blowing up? [Orbán] said, ‘Because you need Trump back as president. They were afraid of him. China was afraid.’ And I don’t like to use the word afraid, but I’m just quoting him. ‘China was afraid of him. North Korea was afraid of him.’ Look at what’s going on with North Korea, by the way. He said ‘Russia was afraid of him.”

Trump has also claimed that he threatened to strike Moscow if Putin attacked Ukraine, though it’s not quite clear when this was since Russian troops were in Ukrainian territory throughout the entirety of Trump’s presidency.

It’s also not clear that US adversaries were deterred by Trump’s tough-guy posturing. Trump has maintained that the punishing sanctions he put on Iran after withdrawing from the nuclear deal stopped it from orchestrating attacks in the region, but he had little response after Iran attacked Saudi oil infrastructure in 2019.

The killing of Soleimani did not stop Iran’s proxies from attacking US troops in Iraq. When it comes to Taiwan, he has suggested that the island is simply too small and insignificant to be worth defending — the kind of rhetoric that would surely influence China’s calculations over a possible invasion.

Once more unto the breach?

At the moment, world affairs seem to be in a bit of a holding pattern, with leaders not making major decisions until they see the results of November 5. Trump may have soured a bit on his onetime good friend Benjamin Netanyahu, but in all likelihood — based on his past record — he would apply even less pressure than the Biden administration has to get Israel to reach a ceasefire in Gaza or allow in more humanitarian aid. A Trump win would likely embolden annexationists within the Israeli government, including the once-fringe but increasingly vocal movement in favor of reoccupying Gaza with Israeli settlers.

On Ukraine, Trump has promised to end the conflict immediately. Judging by comments made by his running mate JD Vance, though, this would likely involve pressuring Ukraine to both cede territory to Russia and accept neutrality, without security guarantees — not far from Putin’s desired outcome. When it comes to China, the outlook is more unpredictable. Trump portrays himself as the ultimate China hawk, except when he believes doing so is bad for business.

Ultimately, the question is not whether Trump is a hawk or a dove. It’s what a return of the chaos and unpredictability that marked his first tenure will mean in a world where the risk of cataclysm is now so much higher.