evidence: A video widely shared on social media in late May shows a man, wearing a bulletproof vest marked with the logo of a Mexican cartel, carrying a weapon that looks like an AT4 anti-tank rocket launcher. The Russian ambassador to Mexico joined in the debate about the video on Twitter, hypothesising that the weapon was likely sent to Ukraine by the West and that the cartel had bought it on the black market. We investigated this video. [...] The Mexican army doesn’t use AT4s. However, there have been a number of videos that have circulated in the past that show narco-traffickers with weapons that look like the AT4 (like this video or this one, both filmed in 2022). Again, however, it is impossible to know if the weapons shown are real rocket launchers or replicas. The specialists who spoke to our team don’t think that cartels have ever used this type of weapon. However, Mexican authorities did seize a number of rocket launchers back in 2020, including several from Tamaulipas. [...] Shortly after the video was posted online in late May, the Russian embassy in Mexico published a tweet in which it insinuated that the AT4 visible in the footage is likely a weapon sent to Ukraine by the West that was then put up for sale on the global black market by corrupt Ukrainian officials. The tweet was viewed 1.2 million times and garnered more than 13,000 likes.