Government department involved in the operation.

The Department of Homeland Security is pushing the I.R.S. for immigrant addresses.

DHS requested the IRS to connect names of potentially undocumented immigrants with their last known addresses.

Government department that announced the plan.

Government agency criticized for its handling of detainees.

The DHS is developing plans to detain migrants at military bases.

The Department of Homeland Security advised employees not to comply with Musk's email.