ICE was not “created from the criminal investigation arm of CBP and related agencies”, it was created at the same time, by the same law, as CBP and DHS, from some of the investigation and enforcement arms of INS and the Customs Service, with much of the rest of those agencies (including the Border Patrol, which had been one of the enforcement arm of INS) becoming CBP, and the routine "happy path" immigration functions of INS moving to USCIS under the Department of State.

> They are related but not the same. Under the current US regime, all the stops are being pulled out and all the lines blurred.

A large part of that is that notional function of the “immigration crackdown” falls logically in ICE's domain, and this was the justification for massively increasing ICE funding, but CBP (and particularly the Border Patrol) having much more of the no-rules culture that was sought for the operation, leading to CBP and Border Patrol personnel taking key roles in the operation (which is why, until he became something of a political scapegoat for the Administration policy, a Border Patrol area commander got redesignated a "commander at large" and then given operational command not just of Border Patrol involvement but the notionally ICE-led operation.)