THE NUMBER of refugees resettled annually in the United States is not intended mainly to solve the world's refugee crisis; given the staggering scale of the problem across the globe, no one country could achieve that goal on its own. But the degree to which Washington opens its door to refugees sends the world a signal about American leadership, confidence and heart. On those counts, the Trump administration is failing.

The admission target for the coming fiscal year is just 45,000 resettlements, by far the lowest since 1980, when Congress enacted legislation enabling the president to recommend an annual cap. That will be understood as an abdication of moral and humanitarian leadership, one likely to encourage other countries to conduct themselves similarly.

The damage done by such a message at this juncture is significant. The world's refugee population stands at 22.5 million, more than half of them children — the highest number since World War II. According to the U.N. Refugee Agency, more than 28,000 people daily are forced to flee their homes because of conflict and persecution. And those figures pre-date the current crisis in Burma, in which a campaign of ethnic cleansing by the military has prompted more than 400,000 Muslim Rohingya refugees to flee across the border to Bangladesh in just the past few weeks.

When Mr. Trump spoke recently at the U.N. General Assembly in New York with the Bangladeshi prime minister, Sheikh Hasina, she mentioned the flood of Rohingya entering her country. The president made no response, according to the prime minister, who said later she expects no help with the refugee crisis from the United States.

In fact, around the world, U.S. allies, including Jordan, Turkey and Kenya, are admitting huge numbers of refugees. In so doing, they act as regional safety valves and forces for stability — and aid U.S. military counterterrorism efforts in those regions. But they take great political risks also. By his stance, Mr. Trump makes their position far more precarious.

Heedless of that interest, Stephen Miller, White House senior policy adviser, and White House Chief of Staff John F. Kelly argued for slashing the annual cap to as low as 15,000, a farcically low number. Pushback from the Pentagon and State Department, among others, limited the damage — but only to a degree. The ceiling of 45,000 set by Mr. Trump represents the first time the cap has fallen below 67,000, the number President Ronald Reagan set in 1986.

The administration makes the disingenuous argument that refugees impose a burden on the United States' resources; in fact, officials from the Department of Health and Human Services found refugees had brought in $63 billion more in local, state and federal revenue than they cost in the decade ending in 2014. That finding was suppressed, but there is no suppressing the fact that the United States is turning its back on the world, and the world's neediest, under the Trump administration.