President Trump signed an executive order on Monday that requires commercial truck drivers in the United States to be proficient in English.

The text of the order acknowledges the essential role that truck drivers play in the U.S. economy and the livelihood of American people.

“Every day, truckers perform the demanding and dangerous work of transporting the Nation’s goods to businesses, customers, and communities safely, reliably, and efficiently,” the order said.

Trump designated English as the country’s official language in an executive order in March. In his order on Monday, the president said proficiency in English should be non-negotiable for professional drivers.

“They should be able to read and understand traffic signs, communicate with traffic safety, border patrol, agricultural checkpoints, and cargo weight-limit station officers,” the order said. “Drivers need to provide feedback to their employers and customers and receive related directions in English.”

“This is common sense.”

Under the order, a driver must be able to read and speak English “sufficiently to converse with the general public” to operate a commercial vehicle in the U.S.

“My Administration will enforce the law to protect the safety of American truckers, drivers, passengers, and others, including by upholding the safety enforcement regulations that ensure that anyone behind the wheel of a commercial vehicle is properly qualified and proficient in our national language, English,” the order said.

The order states that Transportation Secretary Sean Duffy will issue a new guidance on English proficiency testing and enforcement policies. A violation of the English language proficiency requirement would put a driver “out-of-service,” the order said.

“You might not know, but there’s a lot of communication problems between truckers on the road with federal officials and local officials, as well, which obviously is a public safety risk,” White House Press Secretary Karoline Leavitt said during a briefing on Monday.