The other interpretation elides “who are”:
“It was the latest escalation of President Donald Trump’s campaign to deport all immigrants who are in the U.S. Illegally.”
This is similar to a sentence like: “Please point out all the boys eating hot dogs quickly”, which is also ambiguous in the same ways, but I feel shows the intended interpretation more clearly.
Oh man I used to love Ellegarden. Is Nothing’s Carved in Stone worth a look?
I kinda unironically dig this.