With Stephen Miller pick, Trump readies for a battle

Miller is best known for being the driving force behind the Trump administration's aggressive immigration enforcement policies, which has included ramping up funding for enforcement operations across the US.

He made headlines when he called Alex Pretti, who was shot and killed by federal immigration officials during a massive deportation operation in Minneapolis, a "domestic terrorist" and an "assassin". He would later walk back those words, saying federal agents "may not have been following" proper protocol.

He has also reportedly played a leading role in the US military operations in Venezuela and against suspected drug trafficking operations in the Caribbean and eastern Pacific, which critics have condemned as extra-judicial killings.