WASHINGTON, D.C. (Nexstar) — The Trump administration says it is preparing to deploy 100 border patrol SWAT teams across US cities to help ICE agents arrest undocumented immigrants.

They will help ICE agents track down undocumented immigrants with final orders for removal after they are released from local law enforcement custody, ICE said.

According to Hans von Spakovsky with the Conservative Heritage Foundation, there are more than one million unenforced deportation orders at the Department of Homeland Security and ICE agents need extra help.

“They are going to try to use these special units particularly in areas where local authorities are trying to prevent enforcement of federal immigration laws,” he said.

However, Randy Capps with the Migrant Policy Institute says the real goal of the operation is fear.

“The message the BORTAC Team sends is you’re not safe if you live in a sanctuary city,” he said. “It doesn’t matter what the city or the state does to try to protect you, the federal government can still send in a SWAT team after you.”

Massachusetts Democratic Senators Elizabeth Warren and Ed Markey have sent a letter to US Customs and Border Protection asking them to either call off the operation or provide more information about their plans.

The Trump administration is not saying exactly when the SWAT teams will be deployed.