At least in the large airports, the international flights come in to a separate terminal. Will ICE limit their involvement to that terminal only, and only inbound flights? Immigration and Customs have no business on the outbound side or with domestic passengers.
Some international flights arrive in to domestic US terminals. These are from a limited set of countries where passengers have cleared US immigration in the departure country.
Canada, Ireland and the UAE are the major three, plus Aruba, Barbados and Bermuda.
Since they will support tsa operations, I’m going to assume they will be at the outbound security checkpoints. Both domestic and international.