Illinois Senators Dick Durbin and Tammy Duckworth met with Navy officials and toured the Great Lakes Naval Training Station Friday, which the Department of Homeland Security intends to use for logistical support on expected immigration operations this week.

Speaking to reporters after their visit, the senators expressed concern about how the use of the base would affect its mission and purpose, and denounced the administration's plans to send federal agents for immigration enforcement.

Sen. Durbin said they tried to meet with DHS officials, but were told they were unavailable.

"My major concern was to make sure that no exercise of political theater is an obstacle to the mission of the Great Lakes Naval Training Station," said Durbin. "This kind of secrecy is not part of our government and shouldn't be. It's an indication that there's something about this mission they don't want the public to know."

The Trump administration asked the military base outside of Chicago for support on immigration operations this week, offering a clue of what an expanded law enforcement crackdown might look like in the nation’s third-largest city.

The Department of Homeland Security asked Naval Station Great Lakes for “limited support in the form of facilities, infrastructure, and other logistical needs to support DHS operations,” Matt Mogle, spokesperson for the base 35 miles (56 kilometers) north of Chicago, said Wednesday.

The request came weeks after the Republican administration deployed National Guard troops to Washington, D.C., to target crime, immigration and homelessness, and two months after it sent troops to Los Angeles.

Although details of the administration’s plans for Chicago are scarce, city leaders said Thursday that they are preparing for multiple possible scenarios, from troops assisting in immigration arrests to patrolling in the streets.

"We will not allow the diversion of taxpayer dollars that were appropriated for military readiness and military training for Great Lakes to be diverted from that mission, which is critical to our nation's security, into ICE's efforts to intimidate people on the streets of our city. And we've been assured that that will not happen," said Sen. Tammy Duckworth, (D) Illinois. "But we will keep our eyes on it, and we will continue to maintain oversight to what exactly happens."

Duckworth said she would advise Illinois Gov. JB Pritzker not to activate the National Guard.

Mayor Brandon Johnson and Illinois Gov. JB Pritzker have pushed back against a possible mobilization, saying crime has fallen in Chicago and that the city doesn’t want or need the military’s help.