Twice during the first half of the 20th century, Europe erupted into war as imperial powers used force to take land and authority they saw as inherently theirs. On both occasions, the rest of the world was brought into it, causing death and destruction on a scale never before seen in human history.

Since then, the continent has avoided large-scale conflict. The partnerships, structures and ideas built in the aftermath of World War II and strengthened through the Cold War and the subsequent fall of the Soviet Union have prevented it.

A woman holds her baby inside a bus as they leave Kyiv, Ukraine, on Thursday. Russia launched a wide-ranging attack on Ukraine on Thursday, hitting cities and bases with airstrikes or shelling, as civilians piled into trains and cars to flee. Associated Press/Emilio Morenatti

With Russia’s invasion of Ukraine, the postwar order is under direct attack, as are the very concepts of democracy and self-determination. That’s what’s at stake here: the right of citizens of free and sovereign countries dedicated to a stable and peaceful world to guide their nation as they like.

As President Biden said Thursday, the Ukrainian military and the Ukrainian people will bear the brunt of this fight.

But Americans do have a role: To support the Ukrainian people and its government as it defends its rights under international law, and to endure the hit our economy may take as a result.

As the images out of Ukraine show, that’s nothing compared to what others are going through. As shells and missiles fell throughout the country, there were anguished pleas for help and frightened cries from people unsure of what was coming. People packed into subway stations being used as bomb shelters. There were scenes of military aircraft releasing missile after missile, and of rubble on the ground.

The plan appears to be to end the rule of the democratically elected government and install a puppet regime friendly to Russia. Who knows how many Ukrainians, and Russians, will suffer and die, all because of one man and his warped sense of history.

Vladimir Putin has long framed his discomfort with Ukraine in relation to NATO expansion and Western influence along Russia’s border.

That may be part of it. The success of democracy in Ukraine, a country of 44 million on Russia’s border, would certainly make Putin’s life as an autocrat more difficult.

But more than that, Putin has made clear he sees Ukraine as a part of Russia, without any rights to itself, despite its 30 years of independence and its distaste for Russian influence and the corruption it has brought to the country.

Now, Russian artillery is falling on Ukrainian cities, and Russian soldiers are closing in on the capital, if they are not there already.

It’s a breach of international law and of the ideals governing free people, and it must be treated as such. The U.S. and its allies levied sanctions on Russia on Tuesday as troops amassed on the Ukrainian border. Biden announced more on Thursday as the attacks intensified.

The sanctions aim to hit the finances of Putin and his allies in the oligarchy, making them suffer, and perhaps driving a wedge between them, while also sending a message to the Russian people that their leader’s despotic actions are not in the country’s interests.

That will take time. In the meantime, there will be consequences for the world economy, particularly given Russia’s role in the energy markets. On Thursday, the U.S. stock market plunged while oil prices soared. That’s not good news for Americans already struggling to heat their homes and fuel their cars.

What’s more, Putin could escalate cyberattacks against our country, disrupting our economy and lives through technology.

Biden said Thursday the U.S. is prepared for such attacks.

He also should do everything in his power to alleviate the strain in the short term, including gas-tax holidays and increased domestic fuel production, while waiting for the sanctions to squeeze Putin.

Along with our allies, the president should also entertain more harsh sanctions, specifically ones that target Putin himself and his inner circle.

For Americans, it will not be painless. But at least our safety and freedom are not at risk.

In Ukraine, all of those are on the table, and Ukrainians are fighting for them.

In Russia, people who want these same freedoms are taking to the streets to speak out against Putin and his criminal regime, as courageous a stand for democracy as you’ll see.

They’re putting their lives on the line in order to remain part of the free world. That’s something all Americans should support.