President Donald Trump vowed to start his “big beautiful” wall on the Southern border of the United States immediately during an interview with ABC News anchor David Muir.

When asked for the construction date, Trump said that he would begin the project “as soon as we can physically do it” and confirmed that planning would start “immediately.” He predicted, however, that the actual construction process might take a few months to begin.

The president will travel this afternoon to the Department of Homeland Security to sign several executive orders that deal with border security.

Trump confirmed that ultimately Mexico would pay for the wall, but that the government would get the project started.

He also dismissed Mexican President Enrique Peña Nieto for insisting that his country would not pay for the wall.

“I think he has to say that,” Trump replied, vowing that future negotiations with Mexico would ensure payment from the country.

But he suggested that the wall would be good for Mexico too.

“What I am doing will be good for the United States; it’s also going to be good for Mexico,” Trump said. “We want to have a very stable, solid Mexico.”

The full interview airs tonight on ABC News at 10:00 p.m. EST.