The Trump administration has stepped up the rebuilding of the dilapidated U.S.-Mexico border wall and is finally moving on new extensions of the 30-foot-high barrier as it aims to install 500 miles of a new “border system” by the end of next year, officials said on Monday.

Compared to the last wall building effort in 2006 under President George W. Bush, when it took two years to start digging on approved projects, the Trump administration has cut that to 9-11 months, said a senior administration official.

And once the $3.6 billion in money redirected from the Pentagon lands in the hands of border officials, they expect the construction of 2-3 miles a week will surge.

On a day when the administration revealed a dramatic drop in apprehensions of illegal immigrants for a third month in a row, officials also drew attention to the wall building efforts and pushed back at critics who have suggested that the administration wasn’t building anything new.

The officials said that the U.S. Border Patrol’s priority has first been to replace useless walls in key areas, mostly on federal land, where there is a high probability of illegal crossings.

Trump’s team has focused on those areas, installing a new “border system” that includes the high wall, lighting, special technology to identify crossing attempts, and an access road.

“This isn’t a vanity wall of the president’s. It’s not a vanity wall,” said one official. “This president has listened to the experts, and this president is delivering on what the experts have been asking for, make no mistake,” added the official.

Another said, “This isn’t like we’re building in areas just to show progress. We’re building where border patrol said their priorities are.”

In addition to replacing the old wall, the administration has identified a new project for 100 extra miles in the Rio Grande Valley, where illegal crossings are heavy.

Those extra miles will begin soon now that the administration has started to buy private land.

“You are going to see the pace of this construction of new linear miles in areas that were not federally owned before start to accelerate over the coming weeks and months,” said the official on background.