A snake from South America that never made it up the isthmus to the Gulf Coast of North America is not a native species because its from "The Americas". Ecosystems are more specific than that. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
A threat to three US coasts AND to Mexico, Central America and, eventually, to South America as well.
But presumbly it wouldn't be able to survive somewhere on the way down, or it would have made it up to the U.S. by itself anyway.
