U.S. Customs and Border Protection has unveiled a stretch of what it called new wall on the southern border, saying it has completed at least 60 miles of border wall in total.

The section of wall near San Luis, Arizona consists of an 18-foot steel bollard barrier.

CBP says that a new triple-layered enforcement zone is more effective at deterring illegal entry than the former single 10-foot barrier.

That means it is not in fact new wall but a replacement for the existing barrier. The agency has yet to say when it will build any entirely new border barrier.

The agency says that it plans to build at least 450 miles of new border wall by the end of 2020, and has projects underway in California, Arizona, New Mexico and Texas.

The CBP showed this new section of steel bollard wall near San Luis, Arizona

The new wall is in the Yuma Sector, which is the third busiest along the border

The wall near San Luis is in the Yuma Sector, which is the third-busiest along the southwest border.

A majority of the tens of thousands of people who came to the U.S. over the last year are Central American families with children who immediately claim asylum.

Many travel in large groups, and the high volume of people has overwhelmed Border Patrol, resulting in slow response times and dangerously overcrowded detention facilities.

Five children have died while in Border Patrol custody since December.

Some sections of the new wall have three barriers to create a triple enforcement zone

‹ Slide me › Images show mass illegal crossings in 2005 (left) and the new triple-layer enforcement (right)

The administration has awarded $2.8 billion in contracts for barriers covering 247 miles, with all but 17 miles of that to replace existing barriers instead of expanding coverage.

There are already various forms of barriers along 654 miles of the southern border, or about one-third.

On Thursday, construction crews broke ground on another small portion of the $664 million border fence project in the Arizona desert that is funded through President Donald Trump's national emergency declaration.

Crews plan on installing 30-foot steel fencing to replace older barriers on two miles in Organ Pipe Cactus National Monument, next to the official border crossing known as the Lukeville Port of Entry.

A rugged uphill section of the international border wall that runs through Organ Pipe National Monument is shown in Lukeville, Arizona

Construction on border barriers is seen elsewhere in the US in images released by CBP

Work crews erect new border barriers elsewhere in the US in an image released by CBP

The project is funded through the Defense Department. Use of the department's money was previously frozen by lower courts while a lawsuit proceeded. But the U.S. Supreme Court last month cleared the way for the use of about $2.5 billion.

A border wall was a major milestone of the president's election campaign. Congress this year allocated $1.4 billion, but the president wanted much more. He declared a national emergency in February and faced legal challenges for plans to build dozens of miles of fencing almost immediately.

In Arizona, environmentalists have sued over some of the construction contracts, saying the government unlawfully waived dozens of laws to be able to build on protected lands. They say a wall - and construction for it - would be detrimental to wildlife habitat. The case before federal court is pending.