Indeed. The difference between and explicit power [Articles of Confederation] and an implicit power [Constitution]. There are many laws that Congress has made that are implied rather that explicit or specific as you mentioned about immigration. The show me "specifically" in the Constitution argument is "usually" fallacious. Yes of course we have an Air Force as we do enforcement of Immigration, food and drugs laws, work place safety, Communicable disease center, environmental protection etc. I agree there should be some limits but if the States refuse to act, then the Federal government steps in. The problem lies at the State level on many issues that the Federal government takes heat for. My greater and primary point remains and I noticed no one wants to take that on.