The New York Times reported last week that the Obama administration initiated, and the Trump administration inherited, a covert action program to “remotely manipulate data inside North Korea’s missile systems.”

The idea here is straightforward. Instead of just relying on antimissile systems, like the Terminal High Altitude Air Defense (THAAD), which are designed to intercept missiles after they have been launched, you might want tools that would stop the missiles from being launched in the first place. Such “left of launch” tools might include cyber and electronic warfare techniques that sabotage missile components, impair command and control systems, or jam communication signals. They might play a preventive role by, for example, sabotaging North Korean nuclear missile tests. Alternatively, they might preempt an attack that was about to take place, by targeting the basic command, control and communications systems that are used to launch missiles. This might work better than conventional antimissile systems that a U.S. Joint Chiefs of Staff report describes as trying “to hit a bullet with a bullet.”

But “left of launch” approaches may backfire. If a state learns that another state is sabotaging its nuclear program, it might redouble its efforts to implement the program on the basis that the other obviously fears it might succeed.  On the other hand, hidden tools that allow one state to subvert another state’s launch systems or otherwise neutralize its second strike capability might increase instability, by weakening the deterrent power of nuclear weapons and increasing uncertainty.

“Left of launch” cyber attacks, like the ones contemplated in the New York Times report, may be particularly risky in tense standoffs. In a new article in the Journal of Cybersecurity we explain why.

It’s hard to know who can do what with cyber weapons.

States with nuclear weapons can openly advertise their arsenals. This lets other states know that it would be risky to attack them, making misinterpretation and war less likely. They can do this because it is very hard to defend one’s country against nuclear strikes.

Cyber weapons are different. If you are a state and you let potential enemies know about your arsenal of cyber attacks, you are giving them the opportunity to fix their information systems so that they can neutralize the threat. This means that it is very hard to use cyber weapons to make credible threats against other states. As soon as you have made a credibly-specific threat, you have likely given your target enough information to figure out the vulnerability that you want to exploit.

This means that offensive cyber weapons are better for gathering intelligence or actually taking out military targets than for making threats. In this regard, they are the opposite of nuclear weapons, which are more useful as threats than as battlefield options. Nuclear weapons can create stability because they deter attacks. In effect, they create a stable system of beliefs where no state wants to seriously attack a nuclear power, for fear that this might lead to a conflict that would escalate all the way to nuclear war.

Nuclear weapons and cyber attacks don’t mix well.

Unfortunately, this means that the advantages of cyber operations become an important liability for nuclear deterrence when they are used for “left of launch” attacks on nuclear launch systems. By secretly penetrating another state’s launch system, you may undermine the stable system of beliefs that discourages an attack.

Consider what might happen in a tense standoff between two states that both have nuclear weapons, where one state has penetrated the other state’s launch system, so that it could stop a nuclear counter attack. The state that has penetrated the launch system knows that it has a military advantage. However, if  it reveals the advantage to the target state, the target state will be able to patch its system, destroying the advantage. The target state does not know that it is at a disadvantage, and it cannot be told by the attacker.

The result is that the two states have very different perceptions of the situation. The attacker thinks that there is an imbalance of power, where it has the advantage. The target thinks that there is a balance of power, where both states have nuclear weapons and can deter each other. This means that the first state will be less likely to back down, and might escalate conflict, secure in the knowledge that it can neutralize the other state if necessary. However, the target state may too behave in provocative ways that raise the stakes, since it mistakenly believes that at a certain point the other state will have to back down, for fear of nuclear war. Thus, this creates a situation where each side may be more willing to escalate the tense situation, making it more likely that one state will decide to move toward war.

This risk is highest in situations like the U.S.-North Korea confrontation, where the U.S. has real cyber power and might have compromised North Korean missile systems, but where North Korea may falsely believe that it can force the U.S. to back down. The problem for states such as the U.S. in these scenarios is that the tools which make it more likely it will win a conflict, make it more likely that a conflict will occur in the first place.

There is some logic to using “left of launch” attacks to slow down North Korea in building up its arsenal. The problem is that preemptive “left of launch” attacks, which would be used to stop an actual North Korean missile attack may increase the risk of an actual nuclear confrontation.  Cyber operations rely on deception, but nuclear deterrence relies on clear communication. While nuclear crises were rare during the Cold War, they may become a little more common under today’s conditions, and cyberwar may make escalation to thermonuclear war more likely. Thinking about these kinds of cross-domain problems carefully is an important challenge for strategists and national security officials in a new era.

Erik Gartzke is Director of the Center for Peace and Security Studies and a professor at the University of California, San Diego Political Science Department. Jon R. Lindsay is an assistant professor at the Munk School of Global Affairs at the University of Toronto.