The Department of Homeland Security has confirmed it is building a detention centre to temporarily hold migrants in the Florida Everglades.
Secretary Kristi Noem said the facility - dubbed the Alligator Alcatraz - would be funded "in large part" by the Federal Emergency Management Agency's shelter and services programme, which was previously used to fund accommodation and other aid for undocumented migrants.
The plan has been criticised by several lawmakers, including the mayor of Miami-Dade County, who argued it could be environmentally "devastating".
The proposal comes as Trump tries to deliver on a campaign pledge to ramp up deportations of illegal migrants.
"Under President Trump's leadership, we are working at turbo speed on cost-effective and innovative ways to deliver on the American people's mandate for mass deportations of criminal illegal aliens," Noem said in a statement.
