English equivalent of Vietnamese "Rather kill mistakenly than to miss an enemy."

There was a Vietnamese political leader who said during the war, "Thà giết nhầm còn hơn bỏ sót," which translates to "Rather kill mistakenly than to miss an enemy."

I'm wondering if there is a similar saying to capture the spirit. Sayings like "leave no stones unturned" or "spare no expense" seem a bit casual to me.

Edit: Someone also commented about the phrase "Kill them all; God will sort his own". I think that's also very fitting.

Solution 1:

Another English expression that may be on point here is shoot first; ask questions later. Martin Manser, The Facts on File Dictionary of Proverbs (2002) explains the sense of this proverb (which it gives in a slightly different form) as follows:

shoot first and ask questions afterward In certain circumstances—for example, when facing a potentially dangerous person or thing—it is safer not to lose time weighing up the situation before taking action; often used in contexts criticizing such hasty or arbitrary behavior: "It struck her, too, that war seemed to have made the people on that side of the ocean extremely ready with weapon. They would be quite likely to shoot first and ask questions afterward—which would be too late to be helpful" (Mary Roberts Rinehart, The Amazing Interlude, 1918).

Solution 2:

Perhaps "Kill them all and let God sort them out." which actually has a much earlier source than I would have suspected, going back to an incident in modern France in 1209.

Solution 3:

There is an expression in English called Blackstone's ratio that expresses the opposite sentiment (it's very well-known, even if people don't always know its name):

It is better that ten guilty persons escape than that one innocent suffer.

Sometimes this aphorism is deliberately inverted to have a meaning very much like the quote you've translated:

It is better that ten innocent men suffer than one guilty man escape.

Because Blackstone's ratio is so famous in English-speaking countries (and is supposed to be a foundational principle of the justice system in many of these countries), this inversion is usually not sincerely stated. It's more often attributed to others as a way of pointing out unjust or authoritarian systems. You could even replace "suffer" with "be killed" to more closely approximate the original Vietnamese quote and most English-speakers would recognize the reference.

Solution 4:

If the OP wants an expression that is specifically, literally, about killing, then the answers already given are on point, particularly those that trace back to the Albigensian Crusade.

If, however, it is sufficient to convey a figurative sense of "doing something bad in order to be safe", or "expeditious / pragmatic evil", then here are two that haven't been suggested yet:

Better safe than sorry / It's better to be safe than sorry Typically this is used to mean it is better to be cautious, not hasty, so that one does not make a mistake. However it can be used in the sense of being unjustly incautious, violating the rights or safety of others in order to protect oneself. Such a usage would be easily understood in media like films and video games.

It's easier to ask forgiveness than to get permission It is better to expediently get done what you want, even if others will consider it wrong; you can offer an insincere apology later, after you have benefitted from your actions.