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Top White House aide Stephen Miller made a combative Face the Nation appearance Sunday, doubling down on President Donald Trump’s promise to shut down the government if Democrats don’t approve funding for a wall spanning the United States’ 1,933-mile border with Mexico in the next week.

“Absolutely,” Miller affirmed when asked if a government shutdown was on the table.

.@margbrennan asked White House Senior Advisor Stephen Miller if there will be a partial government shutdown over a border wall. Miller says “If it comes to it, absolutely.” pic.twitter.com/qRijkp4jaA — Face The Nation (@FaceTheNation) December 16, 2018

The border wall holds great symbolic significance to Trump and his most fervent supporters after it featured loudly in his 2016 campaign. The cost of such a wall would be astronomically expensive—one internal government report obtained by Reuters put the price tag at more than $21 billion. Trump has been demanding Democrats approve $5 billion for the border wall in an upcoming spending package.

While Democrats have argued the wall is expensive, unnecessary, and unlikely to deter illegal immigration or smuggling, recent Border Patrol crackdowns on immigrants and asylum seekers have shed light on the dangers already faced by people attempting to cross into the United States.

In early December, a 7-year-old girl identified as Jakelin Caal Maquin died of dehydration in federal custody after traveling with her father from an impoverished region of Guatemala. Her death has sparked outrage among immigrant rights advocates and some Democrats, who say it is symbolic of an already dangerous system that would be made even more deadly if the wall is built.