More than a dozen U.S. Immigration and Customs Enforcement (ICE) special agents have signed a letter to Homeland Security Secretary Kirstjen Nielsen calling for reorganization of their agency.

At least 19 ICE investigators signed the letter to Nielsen, saying they were concerned that the agency's current approach to immigration enforcement is preventing them from carrying out the agency’s other duties.

Investigators “have been perceived as targeting undocumented aliens, instead of the transnational criminal organizations that facilitate cross border crimes impacting our communities and national security,” the letter states.

The agents who signed the letter are members of Homeland Security Investigations, a section of ICE. Agents in the division work on crimes like drug trafficking, cybercrimes and human smuggling, according to The New York Times.

The agents suggested that Nielsen create a second bureau just for their investigations and another for immigration detentions and deportations, the Hill reports.