Rich Lowry, syndicated columnist

When President Donald Trump announced a restriction on travel from Europe in a mid-March Oval Office address, European Union officials erupted in outrage.

The president of the European Commission, Ursula von der Leyen, issued a joint statement with the president of the European Council thundering, “The coronavirus is a global crisis, not limited to any continent, and it requires cooperation rather than unilateral action.”

Just a few days later, von der Leyen advanced her own proposal to ban nonessential travel into the EU.

We are all restrictionists now. In the coronavirus crisis, everyone realizes the importance of borders, even the people who not long ago were ideologically hostile toward them.

Borders mark off the sovereign territory of one people from another. They are a means — if they can be enforced and defended — for a sovereign state to protect its people from invaders, and unwelcome immigrants and goods. They are a tool almost every nation has used to try to keep the coronavirus from gaining a foothold in its population, and to try to keep it from spreading further.

The lyrics of the treacly John Lennon classic “Imagine” — recently performed by celebrities organized by actress Gal Gadot as a balm in this time of distress — have never been so absurdly inapt.

If there were really no countries and the world were as one, we’d be even more vulnerable to whatever threat arises in a city in central China, or anywhere else on the globe.

Of course, travel restrictions haven’t prevented the spread of the disease — there’s no such thing as an airtight seal. But restrictions at least bought governments some additional time, and openness to foreign travel from China has been an accelerant on its spread.

The EU travel restriction was an attempt to hold off the hardening of borders between EU nations themselves. Austria, Slovakia, Hungary, the Czech Republic and Poland tightened their borders without coordinating with other EU countries. Even Angela Merkel’s Germany, which provided the kindling for populist movements across the continent with its open-borders approach to the 2015 migrant crisis, restricted travel without coordinating with its neighbors.

Such restrictions are the least of it. Italy has had trouble importing masks because European counties have been working to hold on to medical supplies, indeed to hold on to food. According to the Wall Street Journal, “German officials said their restrictions were partly designed to safeguard supplies at German supermarkets from French shoppers.”

So much for a new era of European solidarity dissolving historic, centuries-old political and cultural divisions.

In a crisis, no one says, “Please, ship overseas medical gear we might need here at home — we are citizens of the world too broad-minded to care about the interests of our own people over the interests of anyone else.”

And no government has acted this way, whether right, left or center; whether led by cosmopolitans or nationalists; whether in Asia, Europe or North America. Everyone realizes their foremost obligation is to their own.

Of course, Trump is naturally inclined to this view. He imposed travel restrictions even before he was truly seized with the seriousness of this crisis. The pandemic gives new credibility to his dim view of our commercial entanglement with China and, before this is all over, there will probably be bipartisan legislation to minimize our dependence on Chinese-manufactured pharmaceuticals and medical equipment.

None of this means that we shouldn’t wish other counties well, help them if we can, and share research and technologies. But borders exist for a reason. All peoples have their own governments that, if they are doing their jobs, put the health, safety and welfare of their own people first.

The coronavirus has acted as a solvent on a decade or more of cliches about the arrival of a globalized world where old lines drawn on a map no longer matter. In a crisis, everyone turns to borders as a first line of defense.

Editor’s note: Rich Lowry is on Twitter @RichLowry.