SAN DIEGO — The Biden administration on Tuesday announced steps to address harm to thousands of families that were separated at the U.S.-Mexico border, expanding efforts to quickly undo relentless changes to immigration policy over the last four years.

President Joe Biden planned to sign orders on family separation, border security and legal immigration, bringing to nine the number of executive actions on immigration during his first two weeks in office. Details were thin, but the moves aim to reverse many of former President Donald Trump's policies to deter immigration, both legal and illegal.

Alejandro Mayorkas, whose nomination as Homeland Security secretary awaits Senate confirmation, will lead a task force on family separation, focused largely on reuniting parents and children who remain apart. It is unclear how many, but about 5,500 children have been identified in court documents as having been separated during Trump's presidency, including about 600 whose parents have yet to be found by a court-appointed committee.

"The task force will report regularly to the President and recommend steps to prevent such tragedies from occurring again," the Biden administration said in a statement.

The review of border security includes a policy to make asylum-seekers wait in Mexican border cities for hearings in U.S. immigration court. It is a step toward fulfilling a campaign pledge to end the Remain in Mexico policy, known officially as Migrant Protection Protocols, which enrolled nearly 70,000 asylum-seekers since it began in January 2019. 

The White House said it will "create a humane asylum system" by rescinding or reconsidering Trump policies that caused "chaos, cruelty and confusion." It warned that it will take time, which may cause grumbling among some pro-immigration advocates.

"The situation at the border will not transform overnight, due in large part to the damage done over the last four years." the White House said in a statement. "But the President is committed to an approach that keeps our country safe, strong, and prosperous and that also aligns with our values."

Roberta Jacobson, a top Biden aide on border issues, asked Spanish-language media on Friday to discourage audiences from coming to the U.S. border. "It is not the moment," she said in Spanish, adding that the journey was "very dangerous, and we are in the middle of creating a new system."

The White House will also do a "top-to-bottom review of recent regulations, policies, and guidance that have set up barriers to our legal immigration system." It will include a review of Trump's "public charge rule," which makes it more difficult for people who use government benefits to obtain green cards.

The moves demonstrate that, just as Trump remade immigration policies from the White House, Biden can undo them with the stroke of a pen — some more easily than others. On his first day in office, Biden halted work on a border wall with Mexico, lifted a travel ban on several predominantly Muslim countries and reversed plans to exclude people in the country illegally from the 2020 census. He also ordered efforts to preserve the Deferred Action for Childhood Arrivals program, known as DACA, which has shielded hundreds of thousands of people who came to the U.S. as children from deportation. 

More lasting changes must pass Congress, a daunting job that Trump and his predecessors Barack Obama and George W. Bush failed to achieve. Also on his first day in office, Biden proposed legislation to give legal status and a path to citizenship to everyone in the country who doesn't have it — an estimated 11 million people.

Biden promised far-reaching changes on immigration during his campaign, but it was unclear how quickly he would tackle the lightning-rod issue. His first-day actions delighted and surprised many pro-immigration advocates who are now being asked for patience.

It is unclear when Biden will lift bans on many temporary work visas and green cards that took effect after the coronavirus pandemic struck or when he will stop allowing authorities to immediately expel people at the border on public health grounds without an opportunity to seek asylum.

Esther Olavarria, deputy director of the White House Domestic Policy Council for immigration, said at a U.S. Conference of Mayors meeting last month that an executive order aimed at "restoring sanity at the U.S.-Mexico border" would end the Remain in Mexico policy and agreements that the Trump administration struck with Guatemala, El Salvador and Honduras for the U.S. to reject asylum applicants and instead send them to those Central American countries with an opportunity to seek protection there.

Olivarria told the mayors to expect an order that restores the U.S. refugee resettlement program after dramatic cuts under Trump but that measure was not included in Tuesday's announcements.