The visualization is driven by the Stockholm International Peace Research Institute (SIPRI) database and it tracks only what is calls "major weapons" (see secti

The visualization is driven by the Stockholm International Peace Research Institute (SIPRI) database and it tracks only what is calls "major weapons" (see section 3 in https://sipri.org/databases/armstransfers/sources-and-methods https://sipri.org/databases/armstransfers/sources-and-method...). So small guns or similar arms will not be covered. Also, I have not checked the dataset yet, but from the description, a chord diagram of source and destination nations could probably be plotted from the SIPRI database. Would make for a good spare-time dataviz project!