The NYPD has come up with a compelling retort to the idea that it's running a stop-and-frisk operation that should die. A week after federal Judge Shira Scheindlin appointed a federal monitor to ride herd on the embattled program, the NYPD announced the largest gun bust in city history. The details are a reminder that stop and frisk needs mending -- not ending.

The final box score on the gun takedown: 19 people under arrest, accused of taking part in a gunrunning ring stretching from the Carolinas to Brownsville, Brooklyn, and 254 firearms confiscated -- 243 handguns, nine rifles and two shotguns. Among this weaponry, say police, were fully automatic assault weapons and a machine gun.

Then comes this priceless snippet of conversation that police overheard on a wiretap: "Yeah, I'm in Charlotte now. I can't leave until you come, 'cause I can't take [the guns] to my house, to my side of town, 'cause I'm in Brownsville . . . We got like -- whatchamacallit -- stop and frisk." Score one for the NYPD.

As the conversation makes clear, whatchamacallit has its uses. The program needs to continue in a form that meets constitutional standards by not unfairly targeting minorities -- in particular young black and Hispanic men.

Unfortunately, City Comptroller John Liu, a Democratic candidate for mayor, says he'd ban the program if elected. The other Democrats in the race take a more weasily tack -- offering ideas in multiple shades of gray.

Public Advocate Bill de Blasio's television ad says he's "the only candidate to end a stop-and-frisk era that targets minorities." But what does that mean? Would he kill the program? Or would he try to fix it?

There are multiple ways to fight the bloody presence of illegal guns on the streets of America. A tighter national mandate for gun background checks is one. Tougher laws from states that regularly export illegal guns, like North and South Carolina, are another. Then there's whatchamacallit. The next mayor must insist on an aggressive, interventionist program that does not make illegal stops on the basis of race or ethnicity. New Yorkers need to get this one right.