ATF officials didn't intend to publicly disclose their own role in letting Mexican cartels obtain the weapons, but emails show they discussed using the sales, including sales encouraged by ATF, to justify a new gun regulation called "Demand Letter 3". That would require some U.S. gun shops to report the sale of multiple rifles or "long guns." Demand Letter 3 was so named because it would be the third ATF program demanding gun dealers report tracing information.