A hierarchical circle-packing visualization displays the distribution of militant organizations across ideological categories and time periods. The code uses D3.js to produce a packed circle layout, encoding each organization as a leaf node with a clipped text label, while internal nodes represent hierarchical groupings. Data is sourced from a JSON file with a nested structure. The visualization is rendered using D3’s `pack` layout, `d3.group`, and SVG elements, with circles colored by tree depth and a drop shadow filter applied for visual separation.