Comment by ben_w

My guess would be that an actual catapult and an RC car would be enough. It may be necessary to be airborne to cross the land border, but only just enough for the physical barrier, the rest can be on land.

That said, I doubt they even bother with such small-scale trade. The narco-submarines are much higher capacity and now apparently well-built enough to be trans-pacific: https://en.wikipedia.org/wiki/Narco-submarine