[azernik]

There are commercially available drones that can carry a payload of high-single-digit to low-double-digit kilograms for at least 10km.[1] They fly low enough and are small enough to avoid most radar.

Their use in cross border smuggling of weapons and drugs is well documented[2]; interception rate is low enough that they can make multiple runs before being downed, and they can pay back their purchase cost with only a few successful runs. Typical concept of operations is similar to manned ground crossings, but with drones covering the most dangerous 5-10km of actually crossing the border: a team on one side loads them up and sends them to a team on the other side, with both having a LOT of real estate to hide in because of the drone's range.

(I work on counter drone EW, and border-control customers are under intense pressure to get this under control.)

[1] Just from DJI, see e.g. the Matrice 400 [https://enterprise.dji.com/mobile/matrice-400/specs], with 6kg payload and approximately zero purchase controls; or the T25 [https://ag.dji.com/mobile/t25p/specs], with >20kg of payload capacity, and even in restrictive regulatory regimes only requiring a shell crop spraying company to buy.

[2] https://www.maariv.co.il/news/military/article-1183896