HIS BOLD initiatives to juice the U.S. economy and overhaul the country’s infrastructure suggest that Joe Biden’s presidency is marked by ambition and a stiff spine. On admitting refugees from the world’s most violent and bedraggled countries, however, he has been timid. Whatever the reason, the White House is mum.

This nation was built by refugees, and for decades they have been admitted legally — thoroughly vetted, carefully placed and backed by a bipartisan majority in Congress. On taking office, Mr. Biden signaled that he intended to go big on refugees, reversing his predecessor’s un-American campaign to slam the door on them. And then . . . nothing.

Having alerted Congress that he would accept up to 62,500 refugees — quadruple the latest cap set by President Donald Trump — in the remaining months of the current fiscal year, which ends Sept. 30, Mr. Biden then failed to sign a routine follow-up directive to activate that plan. At the current snail’s pace of admissions, the Biden administration will take in roughly 4,500 refugees in the current fiscal year, barely a third of the already record-low number who arrived in Mr. Trump’s final, covid-cramped year in office.

The numbers are a blatant betrayal of Mr. Biden’s public commitment, and they have real-world impacts. Pregnant women in Africa and the Middle East who, based on his position, had every reason to think they would soon board a plane bound for the United States, may now be in their third trimester, ineligible to fly. Clearances for other refugees may also lapse owing to the delay. In the meantime, the suffering will only deepen for Iraqis who assisted U.S. Special Operations forces, Syrians fleeing a civil war’s devastation, and Somalis, Congolese and others eager to build new lives after having escaped the world’s most shattered places.

Mr. Trump slashed refugee caps in each year he was president — to a record low of 15,000 he set for 2021, from the 110,000 he inherited from President Barack Obama in 2017. Actual refugee admissions also plummeted during his tenure, to fewer than 12,000 in fiscal year 2020 from nearly 54,000 the year he took office.

It’s extraordinary to think that Mr. Biden, who recognized the United States’ commitment to its history as a safe harbor and promised to rebuild the refugee program, would further decimate it. At the moment, however, he is on course to do just that.

The White House has offered no explanation for his inertia, perhaps because none would suffice. It is true that by slashing the numbers of refugees the United States accepted, Mr. Trump gutted the agencies charged with resettling them. Yet Mr. Biden could at least get the rebuilding process started. It is likely that some Republicans would seize upon a revived legal refugee program, conflating it with the unauthorized surge of thousands of Central American minors and families crossing into this country at the southern border. But that would suggest political cowardice on the president’s part, for which he has supplied scant evidence on other issues so far in his term.

Mr. Biden owes an explanation for what has started to look like his administration’s most consequential flip-flop. The optics are bad enough. The actual costs, in real distress and suffering, are incalculable.

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