President Trump has swung from calling the coronavirus pandemic “totally under control” to a “national emergency” and back. Trump’s latest idea that the nation could be “opened up and just raring to go by Easter” did not stand up to scrutiny. Amazingly, we are months into this crisis and the president is still struggling to get it right.

But what if the president needs to get a decision right the very first time, no do-overs? And what if the wrong decision could lead to a disaster even worse than COVID-19?

Chillingly, that is where we find ourselves on another underappreciated but even more catastrophic threat: —nuclear war. Instead of a relatively slow-moving pandemic, this crisis could have involved strategic warning of a massive Russian nuclear attack. The president would have not weeks but just minutes to decide if the attack was real and, if so, whether to launch U.S. nuclear weapons before the attack arrives. If he decides to launch, there is no going back. No mulligans.

What would the president do? Judging by the coronavirus experience, Trump would likely be uninformed about the specifics of the threat and so would fall back on his gut instincts, assume he knows best, and proceed with dangerous over-confidence. But unlike the current crisis, he would only have time to consult with a few advisors, under intense time pressure, and only if he chooses to. The president has the sole authority to order the launch of U.S. nuclear weapons with no oversight from Congress, the Secretary of Defense, or anyone else.

Trump’s initial response to COVID-19 was to downplay the threat because, presumably, he didn’t understand it. By the same logic, his response to a possible nuclear attack could be the exact opposite: to overrespond by ordering a full-scale, immediate retaliation. Why? Because he is unlikely to understand the nuclear threat, either, and the less he knows the more likely he is to launch.

It is a deeply troubling reality that if early warning systems show a massive nuclear attack on the way, the president might decide to launch an immediate retaliation and has the absolute authority to do so. This would be a catastrophically bad decision for a number of important reasons, none of which may be obvious to an uninformed president.

First and foremost, the president might not know that the attack is probably a false alarm. There have been multiple false alarms like this in the United States and Russia, and the rise of sophisticated cyberattacks make this danger even worse. Meanwhile, both sides know that an actual strike would invite a massive retaliation from the other, and so would be suicidal. A U.S. launch in response to a false alarm would mean we had started nuclear war by mistake, the ultimate nightmare.

Second, if the president is told he must launch U.S. weapons quickly to avoid losing vulnerable land-based missiles, he might not know that he does not need these weapons anyway; there would still be hundreds of nuclear weapons based on submarines safely hidden at sea. The U.S. could mount a devastating retaliation later, so there is no need to rush.

Third, the president might think that a nuclear launch could be recalled. Not so. Unlike a premature decision to reopen the economy, once nuclear-armed missiles are fired there is no bringing them back. It would be the end of the world as we know it.

As bad as things may get with the coronavirus, the situation pales in comparison to a nuclear conflict where hundreds of millions would die and civil society would cease to function. Forget about finding a hospital bed; there would be no hospitals, no respirators, no doctors. There would be no way to mitigate the consequences, no way to “flatten the curve.” When it comes to nuclear war, our only hope is prevention, and the only way to do that is to have the right policies in place to reduce the chances that nuclear weapons will ever be used.

The good news is that maintaining an effective defense does not require us to rush into nuclear war; rather, we need to increase the decision time from minutes to hours or days, which—just like on COVID-19—would allow for consultation. Congress is already considering two ways to do this: a blanket prohibition on the first use of nuclear weapons and/or a requirement for Congress to approve any decision to launch first. Both approaches should provide essential limits on the dangerously free reign the president has now.

If President Trump handles a potential nuclear attack the same way he is handling this pandemic—that is, badly—we are in big trouble. We need to limit the president’s unchecked and unnecessary authority to launch. Trump’s reckless mistakes on COVID-19 are a call to action: we cannot allow the president to make a unilateral decision to start nuclear war.