Federal immigration agents under President Donald Trump have set a new record for arrests of undocumented immigrants who don't have a criminal record, according to data released Thursday.

Under President Barack Obama, Immigration and Customs Enforcement agents focused their efforts on arresting undocumented immigrants who had been convicted of crimes while living in the U.S. During Obama's final month in office, 82 percent of people arrested by ICE had a criminal record, meaning just 18 percent of all arrests were of people who were simply undocumented and had committed no other crimes.

Trump campaigned on a promise to target "bad hombres" – including murderers, violent criminals and gang members – but after assuming office he ordered ICE to arrest all undocumented immigrants it encountered, no matter their criminal background. That has led to a consistent drop in the percentage of people arrested by ICE who have a criminal record.

According to data released Thursday, that percentage fell to 63.5 percent in December, the lowest monthly figure since ICE started categorizing arrests in 2012. That means 36.5 percent of the arrests were simply undocumented with no criminal history.

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Douglas Rivlin, communications director for America's Voice, a group that advocates for immigrants, said Congress provides ICE with only enough money to deport about 400,000 people a year. Using those limited resources on undocumented immigrants with no criminal record, he said, shows that Trump views the issue as more of a political issue than a law enforcement one.

"We're wasting resources deporting a lot of people who are assets to their communities who have families and mortgages and careers and car notes, and we're going after them with the same vigor that we're going after kidnappers and murderers and bank robbers," Rivlin said. "That's not a smart approach to law enforcement."

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ICE officials say all undocumented immigrants have technically committed a crime, either by entering the U.S. illegally or by staying in the country after his or her visa expired.

"One hundred percent of those arrested ... are immigration violators," Nathalie Asher, acting executive associate director for ICE Enforcement and Removal Operations, said during a call with reporters on Thursday.

The dramatic change in the way ICE arrests undocumented immigrants came following a February 2017 directive from the Department of Homeland Security that instructed all immigration agents to target all undocumented immigrants.

Under Obama, ICE agents pursuing a specific undocumented immigrant with a criminal record were under orders not to round up everyone else they found along the way. That meant ICE agents raiding a house to find an undocumented immigrant with a violent criminal record, for example, were not supposed to question everyone else living there about their immigration status.

Through a series of Homeland Security memos issued in February 2017, one month after Trump took office, those restrictions were removed.

"Department personnel have full authority to arrest or apprehend an alien whom an immigration officer has probable cause to believe is in violation of the immigration laws," one memo read. "They also have full authority to initiate removal proceedings against any alien who is subject to removal under any provision of the (Immigration and Nationality Act)."

ICE agents have followed through. They have arrested an average of 4,219 undocumented immigrants without a criminal record each month of the Trump administration. In the final two years under Obama, the agents averaged 1,352 such arrests a month.

The new numbers released Thursday also show a drop in the overall number of arrests made by ICE agents. The 11,178 undocumented immigrants arrested in December mark the lowest monthly total of the Trump administration, which Asher said is a direct result of the migrant caravans that have been flooding the southwest border.

Border Patrol agents and Customs officers are the ones who first come into contact with Central American families and unaccompanied minors that have been crossing the southern border in record numbers in recent months. But Asher said she's been forced to reassign ICE agents to help process those migrants for prosecution, detention, asylum interviews and deportation.

"I have a finite number of officers," Asher said. "We are having to work lock-step with (Customs and Border Protection) redirecting countless numbers of deportation officers to address what’s occurring on the border at this time."