The US and Russia are engaged in a dangerous, unsettling test of wills that could turn into a full-scale war. The risks of that outcome are enormous: a conflict between the world’s two largest nuclear powers would produce 90 million immediate deaths, along with countless others from radiation poisoning and long-term effects of nuclear fallout.

The tensions sparked by Russian aggression in Ukraine are a reminder of the vast differences between Washington and Moscow in their views of the strategic situation. While the Obama administration sees Putin’s authoritarian regime and a growing assertiveness abroad as serious threats, Russia’s leadership sees an adversary that is intent on reversing the illiberal trends of recent years.

A protracted war also harms the United States’ global interests. It reduces the capacity of multilateral institutions, such as the UN Security Council, to work together on shared challenges. Persistent sky-high tensions with Russia will further damage cooperation on such issues as nonproliferation and global energy markets. Russia’s deepening military cooperation with Iran during this war—at a time when Tehran is reneging on its commitment to restrain itself—suggests that it could play the spoiler on such issues.

Moreover, while it is difficult to imagine that a full-scale war between the US and Russia will actually break out, it’s important to have a public discussion about the risks. The risk of a major conflict with China, too, has increased as Beijing’s economy becomes more entwined with those of other nations. A Chinese-US confrontation could have massive economic consequences for Europe and the rest of the world, and European leaders should make clear to their citizens that they are not neutral bystanders in any great power conflict.