They're already trying it and Guatemala is turning the caravans away.

Trump informed the Mexican government he would increase tariffs if they did not protect the US-Mexico border so they in turn put pressure on Guatemala to take care of business.

The Guatemalans are putting the Hondurans on buses and sending them back under pressure from Mexico.

https://nypost.com/2020/10/03/honduran-caravan-aims-for-us-border-mexico-suggests-election-link/

https://www.latimes.com/world-nation/story/2020-10-02/another-migrant-caravan-is-headed-toward-the-united-states