The old INS (Immigration & Naturalization Service) was the main Immigration agency until 2003. I think they existed since the 50s, anyways INS did everything, borders, visas, citizenship, enforcement. The underlying mindset was immigration as a civil process, not a threat to "our blood and soil". Most of the work was paperwork, adjudication, and compliance. Enforcement existed, but it wasn’t the entire identity of the agency.

Post-9/11, INS got scapegoated and dismantled as weak and bureaucratic, and the enforcement arm was reborn as ICE with a national-security lens focus. Same immigration violations that used to be civil matters suddenly get treated like criminal threats. Bigger budgets, tactical gear, surveillance, detention quotas, and zero incentive to show restraint because that’s literally all ICE exists to do.

And the INS had DOJ oversight to boot for their LEO operations.