The FBI often works in conjunction with other Federal agencies, including the U.S. Coast Guard (USCG) and U.S. Customs and Border Protection (CBP) in seaport and airport security, and the National Transportation Safety Board in investigating airplane crashes and other critical incidents. Immigration and Customs Enforcement Homeland Security Investigations (ICE-HSI) has nearly the same amount of investigative man power as the FBI, and investigates the largest range of crimes. In the wake of the September 11 attacks, then-Attorney General Ashcroft assigned the FBI as the designated lead organization in terrorism investigations after the creation of the U.S. Department of Homeland Security. ICE-HSI and the FBI are both integral members of the Joint Terrorism Task Force.

Answer this question, if possible (if impossible, reply "unanswerable"): What are the FBI and ICE-HSI both members of?
Joint Terrorism Task Force