U.S. officials are grappling with a 15 percent surge in illegal immigration, reflecting continued failures by the Obama administration to deter illegal immigration along the country’s southwestern border.

Homeland Security officials apprehended 530,250 illegal immigrants and sent 450,954 people back to their home countries over the 12-month period that ended in September, according to figures released Friday by the Department of Homeland Security.

The majority of those apprehended come from Central American countries and include 137,614 families and unaccompanied children, part of an ongoing flight from high crime and violence in Honduras, El Salvador and Guatemala, which human rights advocates have urged the administration to treat as a refu­gee crisis.

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The number of families and children in the past year also exceeded figures from 2015 and 2014, when illegal immigrants from Central America overwhelmed U.S. Border Patrol stations at the Mexican border and President Obama called the flow of children an “urgent humanitarian situation.”

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Administration officials said Friday that the latest “removal” figures reflect a concerted policy shift to target convicted criminals over others.

“We continued to better focus our interior resources on removing individuals who may pose threats to public safety — specifically, convicted criminals and threats to national security,” Homeland Security Secretary Jeh Johnson said in a statement. “This prioritization is reflected in actual results.” More than 99 percent of those forcibly removed from the country over the most recent 12-month period fell into the administration’s three priority categories.

Overall deportations have dropped over the past few years, from a peak of more than 400,000 during Obama’s first term.

Immigration human rights advocates, including J. Kevin ­Appleby, the senior director of international migration policy at the Center for Migration Studies, say the priorities were a good move — probably resulting in fewer deportations overall — but have come too late.

“In the end, the president will be remembered as a deporter, not a reformer. In the first four years, he set record numbers in removals, much to the dismay of the immigrant community,” Appleby said.

Immigration advocates have repeatedly criticized the Obama administration for its increased reliance on detention facilities, particularly for Central American families, who they argue should be treated as refugees fleeing violent home countries rather than as priorities for deportation.

They also say that the growing number of apprehended migrants on the border, as reflected in the new Homeland Security figures, indicate that home raids and detentions of families from Central America isn’t working as a deterrent.

(Sarah Parnass,Osman Malik/The Washington Post)

According to the Homeland Security report released Friday, U.S. Immigration and Customs Enforcement placed 352,882 people in detention facilities in fiscal 2016, a sharp rise from 193,951 people placed in detention last year.

Officials said Friday that the shifting demographic — from predominantly Mexican adults trying to cross the border 10 years ago to a larger proportion of Central Americans crossing today — has placed an added strain on Homeland Security resources due to the costs of sending people back to Central America and because of longer processes for people with security concerns.

Many of those arriving from Central America have applied for asylum with claims of “credible or reasonable fear of persecution” in their home countries, Homeland Security officials said.

After pressure from immigration rights advocates, the administration last summer announced plans to expand a State Department program to allow Central American minors to apply for refu­gee status.

But human rights activists ­expect detentions to increase under the administration of ­President-elect Donald Trump, who has vowed to step up the deportation of illegal immigrants and build a wall on the Mexican border.

Earlier this month, Trump said he would nominate retired Marine Gen. John F. Kelly, a border security hawk, to run the Department of Homeland Security. Kelly has warned about cross-border threats from Mexico and Central America.

Homeland Security figures released Friday showed that nearly 84 percent of the people removed from the United States in fiscal year 2016 were categorized as Priority 1, which includes ­“national security threats, convicted felons or ‘aggravated felons,’ criminal gang participants, and illegal entrants apprehended at the border,” according to the department’s report.

It was also unclear how many of those convicted were violent criminals or national security threats, as opposed to those whose offenses related only to crossing the border illegally. Twenty-two percent of those sent back to their countries also had no prior criminal convictions, the report said.

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