As part of President-elect Donald Trump’s strategy to secure the border, Immigration and Customs Enforcement will carry out post-inauguration raids as early as Tuesday, sources briefed on the plans told ABC News.

ICE will likely start in Chicago and could move on to other big cities, according to sources, who noted the plans could change.

The agency has been ramping up its operations in anticipation of Trump’s plan to carry out deportations, and the agency put out a request for ICE agents to volunteer to help with at least some of the operations, according to a source.

The plans were first reported by the New York Times and the Wall Street Journal.

Agencies that fall under the Department of Homeland Security umbrella, such as Enforcement and Removal Operations, which handles deportations, and Homeland Security Investigations, have been put on “alert” by the incoming administration, officials with knowledge of the plan told ABC News.

Although field teams have not been given specific details about what next week will hold, federal agents assigned to the region were asked to prepare cases and operations that were “ready to go,” the officials said.

Tom Homan, the incoming border czar, has previewed these operations in past comments, especially targeting Chicago.

In December, Homan visited the city and promised enforcement operations would begin there.

“All that starts Jan. 21, and we’re going to start right here in Chicago, Illinois,” Homan said during the visit.

Homan has promised to go after violent offenders in the United States.