Background Firearm manufacturing and imports grew in the US during the mid-2000s. We hypothesise those increases corresponded to increased international firearms trafficking and in turn were associated with increases in firearm homicides abroad.

Methods We used the Global Burden of Disease database to quantify annual firearm and non-firearm homicide rates in Central American and Caribbean countries, 1991–2019. We obtained US firearm manufacturing and import data from the Bureau of Alcohol, Tobacco, Firearms and Explosives. We used two-way fixed effects regressions to estimate within-country associations between homicide rates (firearm and non-firearm) and US firearm manufacturing and imports.

Findings Firearm homicide rates in Central American and Caribbean countries increased from 8.38/100K population in 2004 to 17.55/100 K in 2012 and remained steady thereafter. Those surges coincided with increases in US firearm manufacturing/imports (from 4.99 million in 2004 to 13.12 million in 2012). Non-firearm homicides remained roughly constant from 1991 to 2019. Adjusted analysis showed that an annual increase of one million firearms manufactured/imported in the US corresponded to an annual increase of 1.42 (95% CI 0.62 to 2.21) firearm homicides per 100 K in Central American and Caribbean countries. The corresponding change for non-firearm homicides was −0.18 (95% CI −1.46 to 1.11). We found country-to-country variability in these effects.

Interpretation Increases in US firearm manufacturing/imports were associated with increases in firearm homicide rates in Central American and Caribbean countries but not associated with non-firearm homicides. The specificity to firearm homicides suggests possible international repercussions of increased firearm manufacturing and imports in the US implications are discussed.