President Donald Trump on Friday again accused Mexico of failing to curb the flow of migrants illegally entering the US, and threatened to close the common border “next week” unless something changes.

Trump’s latest tweets ramp up the tension between the neighbors, putting a specific time frame to his threats to shut the border, one of the busiest in the world.

“If Mexico doesn’t immediately stop all illegal immigration coming into the United States through our Southern Border, I will be closing the Border, or large sections of the Border, next week,” he said.