America has spent the last decade in retrenchment—consider Obama’s eight years of retreating followed by Donald Trump’s isolationism—and the world looks messier than it has in decades. Coincidence? Hardly.

As of Saturday, there is a serious concern about a hot Middle East war, as Iran, directly or through a proxy, struck a major blow to a Saudi oil facility—oil is Saudi Arabia’s dominant source of wealth, and the country itself is the world’s largest exporter of oil. This attack follows a larger trend.

The following events have all happened since the start of August:

Now, add to these major ongoing crises that were not present just ten years ago:

Ukrainian civil war

Syrian civil war which generated a refugee crisis that led to the rise of populism in Europe

Yemeni civil war and the Saudi-Iranian proxy war there

China’s artificial island project

Venezuelan crisis

Libyan civil war

Hong Kong protests

Russia’s general disruption of Western politics and propping up far-right parties in Europe

The international order is becoming less and less stable, and the holiday from history is over. Either directly or with one indirect connection, Iran, Russia, China, and the United States are stakeholders in everything that happens everywhere, and these stakes are often contradictory. If even one conflict becomes too hot and the United States and an adversary have enough at stake on the opposite sides, a great power war is a real possibility.

And the three chief antagonists of the world, Iran, Russia, and China, all have incentives to do it. All three are facing terrible economic problems that are undermining their legitimacy and creating political problems for them. In the past, when states have felt domestically insecure, they have started wars to rally their nations behind their flags and buy themselves time. In fact, Iran was trying to do that just as recently as this summer when they attacked tankers in Persian Gulf and shot down a U.S. UAV in international airspace.

Some experts believe that a balance of power between competitors is the best way to maintain peace. The problem is that history doesn’t support this claim; this was the policy that Great Britain followed before both world wars. Frankly, it’s only America’s hegemony that kept the world a relatively peaceful place since World War II. For the past 10 years, however, by abdicating its hegemonic responsibilities, the United State has been paving the way for revisionists and bad actors to take advantage of a lawless world.

There are reasons for this course of action by the United States. First of all, the United States reduced military spending after the Cold War, and then 9/11 changed the focus of military expenditure to readiness for wars in the Middle East and South Asia. In the meantime, very little money was spent on readiness for potential conflicts in greater Eurasia and research and development.

The Trump administration released a National Defense Strategy (NDS) document with modest aims. Yet, according to then-Secretary of Defense James Mattis and the Chairman of the Joint Chiefs Joe Dunford, an annual 5 percent increase in the military budget would be needed to meet the requirements of the much more modest Obama administration’s NDS. According to a congressionally mandated and bipartisan Commission on National Defense Strategy, the military is terribly unprepared to meet the challenges of the present day to keep the order intact.

The abysmal health of the American public presents a different kind of challenge. Only one in four millennials meets the minimum health and education requirements to be eligible for military service, and that has left all services coming up short on their recruitment goals. This leaves the United States with two options: A public health intervention and/or a move towards artificial intelligence and machinery. The second option requires a significant increase in R&D—a military line item budget that has led to the production of the internet, cloud computing, Siri, GPS, etc. and been left virtually unfunded since the end of the Cold War. And we have decided to pursue neither option so far.

Many of the global problems require just an investment of time and a fair amount of resolve. The more complicated ones require a strong U.S. military. Early intervention in places like Syria, Libya—the 12-day airstrike in 2011 doesn’t really count as a thought-through intervention—and Yemen could have prevented much of the violence those countries have seen, problems which have spilled into Europe and the rest of the Middle East.

But the United States chose not to intervene.

On the morning of June 28, 1914, the world was at peace, and nobody worried about war. That day, Archduke Franz Ferdinand was assassinated. Exactly a month later, World War I broke out. Why? Because the hegemonic power at the time, Great Britain, failed to act.

The United States and the world cannot carry on long like this. A great power war could happen just as fast.

The two frontrunners of the Republican primaries in 2016, Donald Trump and Ted Cruz, advocated for a more modest and populist foreign policy, a promise President Trump is trying to keep. On the other side, Bernie Sanders and Elizabeth Warren, in effect, support the current administration’s retreat policy but with a more diplomatic and articulate tone.

Nobody can predict how long the order could carry on without a war breaking out, but we can be sure that it will eventually collapse if the current trajectory continues.

Populist mantras like “nation-building at home” sound nice, but we can only invest domestically if we are not at war with China or Russia, a war that might not be our choice.

When President Roosevelt asked Winston Churchill what World War II should be called, Churchill responded, “the unnecessary war.” So will be the story if another war breaks out.

The good news is that the United States’ decision to retreat is voluntary and not out of necessity as we still have the means to reverse course. The bad news is that, at least for now, we are just too stubborn to change our mind.