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.)

That trend of blurred lines has been going on for quite a while. Iirc a big callout of the 9/11 commission report was lack of communication between the FBI and the CIA. Even on the local side increasingly it seems every major crime gets a mixture of various federal, state and local law enforcement response.

A notable case was the Uvalde school massacre, which only ended when a border patrol tactical team (believe from the BORTAC group you mentioned) took over from dithering local forces. This was a major example, but interagency collaboration has also become routine in far less dire circumstances.

The militarization and blurred lines have thus become a feature not a bug. And it won't be reformed simply by having the current administration fade into the rearview mirror. It would be beneficial I think though if current excesses led to a more holistic introspection and reform, but we'll see.

In my own country the border guard is part of the military- its a special form of military police. They also protect embassies for some reason.

Trust me the US does not have a patent on bureaucracy... Over the centuries things just develop. One can only assume it made sense once.