President Donald Trump on Monday suggested sending repeat criminal offenders to foreign countries, suggesting the move may cut the government’s spending on prisons, following an escalation of arrests across the country in recent days as part of what Trump has promised would be the “largest deportation operation” in U.

The incoming administration will need to clear a number of hurdles to enact its plan, immigration experts said.

With more than 11 million undocumented immigrants in the U.S., Trump's Operation Aurora would cost billions of dollars.