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Why are short-period comets believed to come from the Kuiper belt?

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asteroid Ida and its satellite, Dactyl — Small body Asteroid Ida and its satellite, Dactyl, photographed by the Galileo spacecraft on August 28, 1993, from a distance of about 10,870 km (6,750 miles). Ida is about 56 km (35 miles) long and shows the irregular shape and impact craters characteristic of many asteroids. The Galileo image revealed that Ida is accompanied by a tiny companion about 1.5 km (1 mile) wide, the first proof that some asteroids have natural satellites.

Short-period comets, particularly those in the Jupiter-family, are believed to originate from the Kuiper belt primarily due to the specific orbital characteristics of these comets.1

Dynamical simulations demonstrate that the high concentration of Jupiter-family comet orbits near the ecliptic—the plane of Earth's orbit—can only be explained by a flattened source of icy bodies. The Kuiper belt, a disk of small bodies extending beyond the orbit of Neptune, matches this geometry.12

In this model, objects within the Kuiper belt—specifically those in the "scattered disk"—experience gravitational interactions with Neptune. These interactions can scatter the objects inward toward the planetary region, where they eventually transition into short-period comets. This theory gained prominence because attempts to explain the supply of short-period comets solely through the Oort cloud proved to be inefficient, failing to account for the observed frequency of these comets.314