The number of migrants requesting asylum at ports of entry along the southwest border doubled in fiscal year 2018 from the previous year, according to Customs and Border Protection data released on Monday.

But the new data also show that the percentage of foreigners who entered the country illegally before requesting asylum stayed flat in 2018, raising questions about the Trump administration's purely law enforcement-focused response to migrant caravans.

In an effort to halt what he's described as an invasion by mostly Central American migrants, President Donald Trump has spent hundreds of millions of dollars to deploy more than 2,000 National Guard troops, nearly 6,000 active-duty military troops, and other federal agents to line the border with concertina wire and prevent large-scale illegal crossings.

The new data from CBP shows a different picture, however, where more migrants are doing exactly what the U.S. government has asked them to do: present themselves at a port of entry to make their asylum claim. Of the more than 5,000 migrants who have arrived in Tijuana in recent weeks, many are planning on applying for asylum in the U.S.

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Asylum is a form of protection granted to people who fear persecution in their home countries based on their race, religion, nationality, membership in a particular social group or their political opinion. From 2000 to 2016, the United States granted asylum to an average of 26,651 foreigners a year, according to Department of Homeland Security data.

In fiscal year 2018, which ended in September, 38,269 people requested asylum at U.S. ports of entry along the southern border, representing 31 percent of those found "inadmissible" by port officers. In 2017, that number was 17,284 people, or 16 percent of those found inadmissible by port officers.

Over the same time period, the pace of people crossing illegally before requesting asylum remained steady. In fiscal year 2018, 54,690 people entered the country illegally before requesting asylum, representing 14 percent of all illegal border crossers that year. In 2017, that number was 38,300, or about 13 percent of all illegal border crossers that year.

A Customs and Border Protection official said the numbers show the new reality along the border, where thousands more people are trying to enter ports of entry and requesting asylum. But he said the federal government is not equipped to handle that rush of asylum-seekers at the ports, forcing his agents to institute "queue management" systems that require migrants to wait on the Mexican side of the borders for days or weeks.

During a conference call with reporters Monday, the official was asked why the government has been able to deploy thousands of troops and construct temporary housing throughout the southern border for enforcement actions, but has not engaged in a similar effort to increase the number of migrants it can process for asylum at ports of entry.

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The official, who spoke on condition of anonymity to discuss the new data before they were publicly released, said any effort to improve asylum claims at the ports would take away from other priorities, like national security and drug interdiction.

"To shift resources away from those other competing priorities so that we would process more migrants…does come at a negative impact of those other missions," the official said. "So every day we try to balance the right mix."

Human rights groups have questioned that approach, with the Los Angeles-based Coalition for Humane Immigrant Rights calling it a "violation" of the federal government's responsibilities to those in most need of help.

The number of asylum applications has skyrocketed in recent years, from 5,000 in 2008 to 97,000 in 2018, mostly fueled by Central Americans fleeing violence and poverty in their home countries.

Federal law allows foreigners to request asylum once they reach U.S. soil, whether they enter through a port of entry or enter the country illegally. The Trump administration tried to end asylum for those who enter illegally, but that move was quickly blocked by a federal judge.

In a statement on Monday, CBP Commissioner Kevin McAleenan said the overall increase in asylum claims along the border requires significant changes from Congress to help his agency deal with the new flow.

"These numbers reflect a dramatic increase in initial fear claims by those encountered on the border, which is straining border security, immigration enforcement and courts, and other federal resources," McAleenan said.

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