President Donald Trump said the country would not survive long unless a wall is built on the border with Mexico during a Tuesday visit to California to look at prototypes of the wall.

“For the people who say no wall, if you didn’t have walls over here, you wouldn’t even have a country,” Trump said. The president also said he wants the wall to have “see-through capability.”

“The state of California is begging us to build walls in certain areas,” added Trump.

Last week the administration sued California for its so-called “sanctuary city” policies laws allowing local law enforcement to refuse to cooperate with federal immigration officials.

Demonstrators in California protested Trump’s arrival and chanted “No ban! No wall,” the AP reported. San Diego Organizing Project member Cornelius Bowser told The Daily Beast, “We value immigrants. Building a border wall is a waste of money.”

Trump declared he would build a wall on the Mexico-U.S. border during his campaign announcement in June 2015.

"I will build a great wall—and nobody builds walls better than me, believe me—and I'll build them very inexpensively,” he said.

“We will build a great wall along the southern border—and Mexico will pay for the wall,” Trump reiterated during an August 2016 rally, shortly before election day.

Mexican President Enrique Peña Nieto responded on Twitter that his country would never pay for a wall. Nieto recently canceled a meeting with Trump over continued “disagreements” over who would fund the border wall, per The Washington Post. This happened all despite Trump reportedly confessing to Nieto during an August 2017 phone call that the wall is actually “the least important thing that we are talking about.”

Days after his inauguration, Trump issued an executive order that called for the wall’s construction as a way to “deploy all lawful means to secure the Nation’s southern border” in order to lower the influx of undocumented immigrants.

Last year, the Department of Homeland Security said the wall could cost $21.6 billion, almost twice as much as Trump’s $12 billion estimate during the campaign. The border wall factored into the immigration debate earlier this year when Trump declared that negotiations with Democrats over the Deferred Action for Childhood Arrivals (DACA) program must include funding for the border wall, as The Daily Beast reported. DACA was set to expire on March 5 until a federal judge blocked the administration from ending the youth-focused immigration program.