That's a relatively large jump to conclusion you made. I doubt there's anyone in the US government (where, exactly, in the hierarchy do you suppose) that would

That's a relatively large jump to conclusion you made. I doubt there's anyone in the US government (where, exactly, in the hierarchy do you suppose) that would have the skill to get that past congress (congress sets the budget for all of DHS btw). As for the missions, from both your links: "The mission of the FBI is to protect and defend the United States against terrorist and foreign intelligence threats, to uphold and enforce the criminal laws of the United States, and to provide leadership and criminal justice services to federal, state, municipal, and international agencies and partners. It performs these responsibilities in a way that is responsive to the needs of the public and faithful to the Constitution of the United States." "HSI conducts criminal investigations against terrorist and other criminal organizations who threaten national security. HSI combats worldwide criminal enterprises who seek to exploit America's legitimate trade, travel and financial systems and enforces America's customs and immigration laws at and beyond our nation's borders." Yes there's quite a bit of overlap there. Maybe the key difference is that ICE's mission talks about customs and immigration laws specifically.