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.
Best Answer
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: