SAN DIEGO (AP) — In the days before Joe Biden became president, construction crews worked quickly to finish Donald Trump’s wall at an iconic cross-border park overlooking the Pacific Ocean, which then-first lady Pat Nixon inaugurated in 1971 as a symbol of international friendship.

Biden on Wednesday ordered a “pause” on all wall construction within a week, one of 17 executive orders issued on his first day in office, including six dealing with immigration.

The order leaves projects throughout the border unfinished — but still under contract — after Trump worked feverishly last year to build 450 miles (720 kilometers), a goal he said he achieved eight days before leaving office.

The Trump administration said it had identified $15 billion to reach a total of 738 miles (1,181 kilometers), but it is unclear how many of those additional miles are under contract and what cancellation fees Biden would face to fulfill his pledge to not build “another foot.” Biden ordered answers within two months on how much the government committed, how much it would cost to extricate itself and whether contracts could be repurposed for other uses.

The White House had no immediate comment Thursday, but given the lack of communication between Trump aides and Biden’s transition team, quick answers may prove elusive.

“It is remarkably opaque,” said Dror Ladin, an attorney for the American Civil Liberties Union who’s scheduled to argue before the U.S. Supreme Court next month that it was illegal for Trump to divert billions of dollars from the Defense Department to build the wall.

John Kurc, an activist who posts videos of dynamite blasts by wall construction crews, said he saw one dynamite charge being set Wednesday afternoon in Guadalupe Canyon in easternmost Arizona, even as the inauguration was playing out in Washington.

Heavy machines have been crawling over roadways gouged into rocky mountainsides, tapping open holes for posts on U.S. Bureau of Land Management property.

In Texas’ Rio Grande Valley, the busiest area for illegal crossings, advocates for the Texas Civil Rights Project saw idle trucks and construction equipment Thursday, though rain may explain the lack of activity.

In San Diego, crews were out Thursday replacing a steel fence with imposing, tightly spaced poles topped with flat steel plates rising 30 feet (9 meters), said Dan Watman of Friends of Friendship Park, a group that promotes public access to the cross-border park overlooking the Pacific Ocean.

Contractors began last week, said Watman, who was informed of the project in a December conference call with Border Patrol agents but got no explanation for it. The agency referred questions to the White House.

Trump said the border wall would be “virtually impenetrable” and paid for by Mexico, which never happened. While the wall is much more formidable than the barriers it replaced, it isn’t uncommon for smugglers to guide people over or through it. Portions can be sawed with power tools sold at home improvement stores.

Despite Trump’s bravado, Border Patrol officials have said the wall was never meant to stop everyone but rather to slow their advance.

Jose Edgar Zuleta, whose business selling religious jewelry in the Mexican city of Puebla dried up during the coronavirus pandemic, cleared two walls in Friendship Park in October with a special ladder. He moved through brush in a heavily patrolled area for about half an hour before getting caught. His 21-year-old son, who went ahead of him, got picked up hours later.

Zuleta agreed to pay smugglers $19,000 for him and his son but only if they made it to the U.S., where they hoped to work as landscapers in Southern California. He returned home to his wife and mother and may try again.

The cross-border park has hosted yoga classes, concerts and countless news conferences, including one in 2018 with then-Attorney General Jeff Sessions to announce a “zero tolerance” policy that caused thousands of children to be separated from their parents at the border.

An old bullfighting ring and ocean-view restaurants surround the Mexican side; wetland scrub stretches into the United States.

Years ago, people passed baked goods, kissed and shook hands through a chain-link fence. Watman remembers passing tools back and forth in 2007 to plant a cross-border garden that still stands.

Since 2012, after construction of a double wall at the park, the Border Patrol has opened a gate many weekends for up to 10 people at a time to exchange words with those in Mexico.

The latest sprint of construction there is part of a $101 million contract to SLSCO Ltd. to build 14 miles (22 kilometers) in San Diego with Homeland Security appropriations.

SLSCO, based in Galveston, Texas, didn’t immediately respond to a request for comment Thursday.

At issue before the Supreme Court on Feb. 22 is billions of dollars that plaintiffs say was wrongly transferred from the Defense Department after Congress denied the money that Trump sought, triggering a 35-day government shutdown in 2017.

It is unclear if Biden will adopt Trump’s position before the Supreme Court. The government’s brief is due Feb. 11.

Mexican President Andrés Manuel López Obrador welcomed Biden’s decision to stop wall construction but, in defense of Trump, noted that U.S. presidents going back to 1990s built border barriers. He displayed a chart to prove his point.

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