The memos also put the agencies on notice that their attitudes and those of their labour unions that endorsed the former president must change.
“As the nation’s premier law enforcement agency, we set a tone and example for our country and partners across the world,” Troy Miller, CBP’s top official, said in his memo. “We enforce our nation’s laws while also maintaining the dignity of every individual with whom we interact. The words we use matter and will serve to further confer that dignity to those in our custody.”
Last month, Mr Biden appointed Kamala Harris, Vice President, to lead the White House effort to tackle migration at the southern border.
Ms Harris’s responsibilities involve diplomatic relations with the Central American countries known as the Northern Triangle – El Salvador, Guatemala and Honduras – where many of the migrants begin their journey.
Both Mr Biden and Ms Harris have faced criticism for declining to visit the border since they took office in January.
It came days after Mr Biden signed an order on Friday limiting refugee admissions this year to the historically low 15,000 cap set under Mr Trump, shelving a plan to raise it to 62,500, drawing the ire of refugee advocates and progressive lawmakers.
However, after criticism mounted over the initial decision, the White House issued a statement later the same day saying Mr Biden would set a final, increased refugee cap for the remainder of this fiscal year by May 15.
Jen Psaki, the White House’s spokeswoman, said the initial goal of more than 60,000 was now unlikely “given the decimated refugee admissions program we inherited.”
The program for admitting refugees is distinct from the asylum system for migrants. Refugees must be vetted while still overseas and cleared for entry to the country, unlike migrants who arrive at a US border and then request asylum.
The president’s cautious approach appears to have been tied to concerns over the optics of admitting more refugees at a time of rising numbers of migrants arriving from Mexico.