Established after the Sept. 11 attacks to protect the country against terrorism, the agency absorbed immigration functions that have become its focus under President Trump.

As ICE and Border Patrol agents increasingly work alongside one another nationwide, it's often become difficult to tell them apart.

ICE stands for Immigration and Customs Enforcement. It was created in 2003, an outgrowth of a policy change after the 9/11 terrorist attacks.

ICE's budget hovered around $10 billion for years. But President Trump and the Republican-controlled Congress are taking the agency's funding to unprecedented levels.

These are the key agencies helping enforce President Donald Trump's immigration policy. - Illustration by Leah Abucayan/CNN/AFP via Getty Images President Donald Trump’s vow to wage the biggest domestic deportation program in American history ...

“ Terrorism is such a powerful label,” Tom Warrick, a former DHS policy official who worked under Presidents George W. Bush, Barack Obama, and Trump, told me this week. “Applying that to Renee Good just defies the average American’s understanding of what that term ought to mean.”

Congressman brands DHS agency 'beyond reform' as he seeks to 'fundamentally change the way we approach immigration.'

WASHINGTON, USA - MARCH 7: The Department of Homeland Security logo is seen on a law enforcement vehicle in Washington, United States on March 7, 2017. (Photo by Samuel Corum/Anadolu Agency/Getty Images) If you’ve been watching reportage and viral videos ...