One year ago, the Zaporizhzhya Nuclear Power Plant—the largest in Europe—became the scene of breathtaking Russian irresponsibility. The world watched footage of combat around operating nuclear reactors as Russia took control of the facility by force.

This flagrant disregard for nuclear safety was hardly an isolated incident in Ukraine. Over the past year, Russia has engaged in a campaign of violence against the basic principles of nuclear security. Such reckless misconduct demands the world’s attention—and our action.

From the start of the war, the Kremlin has made Ukrainian civil nuclear facilities a central target of its military strategy. Russia seized and subsequently looted the Chornobyl Nuclear Power Plant just hours into the invasion, then used the site as a staging ground for its attempt to capture Kyiv. Within weeks, Russian military strikes hit a radioactive source facility outside Kyiv. Days later, Russia repeatedly struck the Kharkiv Institute for Physics and Technology. In September, a Russian missile damaged buildings at the South Ukraine Nuclear Power Plant, and Russian forces have likewise struck a radiological storage site near Kharkiv. And since taking hold of Zaporizhzhya, credible reports indicate Russian personnel have systematically mistreated the plant’s staff, forcing courageous Ukrainian civilians to work through unwarranted detention and even physical abuse.

Just as egregious, Russia has relentlessly rained missiles and drones down upon Ukraine’s electrical infrastructure. Putting aside the cruelty of leaving civilians in the dark and cold of winter, these strikes have further jeopardized the integrity of Ukraine’s nuclear power plants. Safe operation of these facilities depends on continuous offsite power to keep their reactors cool, and even the short-term loss of electricity could spark a terrible accident. Russian leaders are fully aware of this danger and proceeded anyway. At the Zaporizhzhya plant, power outages forced staff to rely on dated backup generators before they ultimately had to shut the reactors down. The Ukrainian people desperately need the electricity produced by the plant, but no one can afford a nuclear emergency.

This heedless behavior has impelled Rafael Grossi, Director General of the International Atomic Energy Agency, to issue the “Seven Indispensable Pillars of Nuclear Safety and Security,” a thoughtful set of self-evident guidelines for nuclear power plants. Yet Moscow has repeatedly violated these principles, just as it has ignored international law on the battlefield.

Russia’s military strategy has already set a perilous precedent for future conflicts. And since its leaders have shown no willingness to step back from their dangerous approach, they are leaving the entire world facing a heightened risk of nuclear catastrophe while this conflict rages on.

We should be under no illusion that an emergency at a Ukrainian nuclear power plant would be confined to Ukraine’s borders. Radiation could spread to other countries—perhaps including Russia itself—and with it, mistrust of nuclear energy. This would be disastrous to the international community’s climate and clean energy ambitions. Nuclear energy is a key source of carbon-free electricity, and its decades-long record demonstrates it is safe—when the rigorous standards guiding responsible use are respected. If Russia’s attack on those standards causes a nuclear disaster, public confidence in nuclear energy’s role within the global energy mix may diminish, along with our ability to overcome the climate crisis.

The global implications of Russia’s pattern of disdain for nuclear safety and security demands a response that is international in character. We can begin by undercutting a source of funding that has helped Russia run its war machine: the export of nuclear reactors around the world. Countries must look toward more reputable, responsible alternatives to Russia’s commercial nuclear industry. Reducing the sector’s profitability would force Russia to pay a price for its actions. It would also send an unmistakable message that the nuclear marketplace will not reward vendors who serially disregard nuclear safety.

After Russia proved itself to be an unreliable energy supplier, using oil and gas as a cudgel against nations who have supported Ukraine, the international community worked together to limit the damage. Nations around the world are now moving to break their overreliance on Russian fossil energy. Russia has repeatedly demonstrated that it is not a responsible nuclear power and supplier of civil nuclear technologies. It must face consequences for those actions.

Jennifer M. Granholm is the 16th United States Secretary of Energy.