The number of migrants detained along the U.S.-Mexico border has increased for the first time in nine months, according to statistics published by the Trump administration Thursday that indicate the president’s deterrent measures may be stalling.

U.S. Customs and Border Protection officials said 37,119 unauthorized border crossers were taken into custody in February, up from 36,660 in January. While the number of migrants arriving in family groups continues to decline, the number of single adult migrants from Mexico and unaccompanied children rose last month, the figures show.

President Trump has campaigned for reelection on his border security record. While the February border numbers do not represent a major increase, analysts say the president could have a difficult time pointing to the monthly enforcement statistics as a sign of his success if an upward trend emerges.

Mexico’s homicide rate remains near peak levels, its economy is not growing, and a slowdown in global manufacturing triggered by the coronavirus spread could create new emigration pressures in the coming months.

Mark Morgan, the acting CBP commissioner, praised Trump’s border policies to reporters Thursday and presented a chart titled “Alien Removals Exceed Arrivals” that he said was evidence of the administration’s success.

Instead of using the monthly arrest figures as a gauge for migration trends — as Trump officials have done for the past three years — Morgan said the new metric shows the administration continues to deport or turn back more immigrants than the number being detained.

“We have become more efficient and more effective at removing individuals,” he said, adding that the agency has reduced the number of migrants released into the U.S. interior by 95 percent.

Though the raw numbers show an increase in unauthorized migration, Morgan said the agency’s new calculations demonstrate “what I call the end of catch-and-release.”

The Trump administration maintains it is still confronting a crisis at the border that requires emergency restrictions on the U.S. asylum system. While the number of migrants taken into custody last month was fewer than half the February 2019 total, it was significantly higher than the 23,557 arrests recorded in February 2017, the president’s first full month in office.

Arrests have dropped 75 percent since May, when authorities detained more than 144,000 border-crossers during a record surge of Central American families and children. The administration responded by imposing sweeping restrictions on U.S. asylum processing, requiring migrants to wait in Mexico while their humanitarian claims are adjudicated or flying them to Guatemala with instructions to seek safety there.

One of those programs, the Migrant Protection Protocols, has sent more than 60,000 back to Mexico to wait while U.S. courts process their claims. Thousands are waiting in makeshift camps and shelters on the Mexican side of the border, where reports of kidnappings and attacks against asylum seekers are commonplace.

The U.S. Court of Appeals for the 9th Circuit on Wednesday upheld an injunction blocking the Trump administration from placing migrants in the MPP program after March 11, but the ruling will apply only to those who cross the border into Arizona or California.

Government attorneys have asked the Supreme Court to stay that injunction and allow the MPP program to continue border-wide.

The president said this week that his administration is prepared to close the southern border entirely in response to the coronavirus outbreak, but there are no indications CBP is taking steps to do so. Mexico has confirmed only a handful of infections, far fewer than the United States.

Ken Cuccinelli, an acting deputy secretary of the Department of Homeland Security, told senators Thursday that CBP has amplified its screening for potential coronavirus cases at U.S. land-border points of entry, in addition to its airports. The agency has “excluded over 300 foreign nationals” at the three border crossings most heavily used by Chinese nationals, some of whom he said had flown to Canada or Mexico in an effort to skirt U.S. travel restrictions pertaining to the coronavirus.

The United States is banning the entry of most foreign nationals who recently visited or departed China. U.S. citizens and permanent residents who recently visited China are subject to additional screening, and thousands — including those who have no symptoms of illness — have been referred for 14 days of self-monitoring and isolation at home.

“It has not been uncommon for Chinese nationals to fly to Tijuana or Vancouver or Montreal . . . and then cross into the United States,” Cuccinelli told lawmakers Thursday at a Senate Homeland Security and Governmental Affairs Committee hearing.

“The three largest land ports of entry for Chinese nationals are Blaine, Washington; Buffalo, New York; and San Ysidro in California,” he said. “. . . At those three ports, the numbers [of Chinese nationals crossing] are sufficiently high that we staged a cooperation with HHS medical personnel there, much like we have at the airport.” Canadian nationals who had recently traveled to China make up the largest group denied entry, he said, followed by Chinese travelers.

“We have been very aware of it and confronting it head on and turning those folks back, frankly,” Cuccinelli added.

Cuccinelli said CBP officials at airports and other ports of entry were giving “obviously a heightened focus” to any travelers who had visited China or Iran, “but also [South] Korea, Italy and Japan.” Travel history is the “first and biggest flag” for CBP officials screening arrivals to the United States, he said. He also said administration officials were reevaluating daily the possibility of an expanded travel ban.

Currently, individuals identified as having visited high-risk areas might be pulled aside for secondary screening. Individuals deemed particularly at risk are referred for medical screenings by contractors on-site at ports of entry, and potential cases are then referred to the Centers of Disease Control and Prevention, Cuccinelli said.