Civ 6: How to stop an AI settler without declaring war

So I was playing a peaceful game, and along came a settler from the strongest AI player to an island that I was also settling on. I was not able to chase it down and surround it with my units, but in a moment of inspiration my own settler offered me a solution: the Civ equivalent of a tractor beam, as I settled a city and bought up the tiles surrounding the AI settler, trapping it in. Enjoy the one-tile rainforest, AI! Just in case you're wondering, the map is the Pacific Rim section on my East Asia map. And the poor AI settler belongs to Ryukyu Kingdom, a modded civ. Saph's East Asia (TSL): Ryukyu Kingdom: Follow me on: ▶ Saph's Maps Discord: ▶ Twitter: ▶ Steam: https://s