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President Trump's recent tweet that El Salvador "just takes our money" and doesn't contribute enough in the fight against MS-13 comes just days after a report was released claiming the gang is relying on a stream of unaccompanied minors entering the U.S. illegally to carry out its violent deeds.

Trump's comments Friday also came following his threat to pull U.S. Immigration and Customs Enforcement officers from California if state officials there continued to stonewall requests from them in regards to immigration initiatives.

"MS-13 gang members are being removed by our Great ICE and Border Patrol Agents by the thousands, but these killers come back in from El Salvador, and through Mexico, like water," he tweeted. "El Salvador just takes our money, and Mexico must help MORE with this problem. We need The Wall!"

El Salvador's Foreign Ministry, in response, said the comments "again, go against the dignity of the country and omit the efforts and contributions” it has made with regional partners in fighting criminal gangs, Reuters reported.

Trump's bruising statement highlights his administration's all-out war on the brutal MS-13 gang, which has been active in at least 22 states, according to a report released last week by the Center of Immigration Studies.

Researchers at the DC-based think tank say through Internet searches they found 506 cases of MS-13 members being arrested or charged with crimes inside the U.S. since 2012, with concentrations being in areas where large numbers of such minors have been resettled through the government.

“They have come back with a vengeance,” Jessica Vaughan, director of policy studies at the organization, said Wednesday on Tucker Carlson Tonight. “This is not just petty gang violence, nuisance crimes. We’re talking murders, hundreds of murders that MS-13 members have been arrested for."

She added: “ICE and other law enforcement agencies were able to stifle it for a while there but in recent years it’s really rebounded because they took advantage of this surge of unaccompanied minors that’s been going on for several years and also the lack of immigration enforcement."

The news comes after a House Committee on Homeland Security meeting in January in which an FBI official reportedly said MS-13 is "very much interested in sending younger, more violent offenders up through their channels into this country in order to be enforcers."

The Center for Immigration Studies, which describes itself as an “independent, non-partisan, non-profit, research organization” providing the public with information on the impact of legal and illegal immigration in the U.S., said in the report the states that had the most cases they analyzed were: California with 92, followed by Maryland (84), New York (80) and Virginia (63).

Among the nationwide stats, 207 MS-13 members were charged with murder and more than 100 were accused of conspiracy/racketeering. It also said the median age of all the suspects identified was 23, and 120 of them arrived on U.S. soil as unaccompanied minors.

“We found that they were active in 22 states just in the last few years and concentrated in those areas that experienced a lot of illegal arrivals from Central America,” Vaughan said. “It’s urban, it’s rural as well in some places that have never had this kind of a gang presence before and it’s difficult for them.”

The report suggests relaxed immigration enforcement under the Obama administration contributed to the influx of unaccompanied minors and families arriving illegally from Central America, claiming 300,000 unaccompanied minors and families were caught by the Border Patrol since 2012.

Data from Fox News shows the number of unaccompanied children apprehended along the southwest U.S. border hit its peak in 2014 with 68,541.

“Under Obama administration policies, most of the families were released and allowed to continue to their destination, with orders to appear for immigration court proceedings that would take place years in the future, but most have absconded from the process,” the report states.

MS-13, which has roots in El Salvador, is then going to some of those minors and tapping them as their next recruits, exploiting their lack of family and community ties, according to ICE.

“Gangs like MS-13 prey on vulnerable members of our communities to recruit new members,” Dani Bennett, an ICE spokesperson, told Fox News. “Sadly, unaccompanied alien children are particularly vulnerable to being recruited by gangs in the United States.

“Unfortunately, once they are recruited into the gang, they can rapidly transform into the lethal MS-13 gang members that they once feared,” she added.

Rep. Lee Zelden, R-N.Y., represents a large portion of Long Island -- an area shaken by MS-13 attacks -- and has introduced legislation this month aiming to revoke the citizenship of naturalized people who have gotten involved with gang activity in the ten years prior to or after becoming an American.

ms-13 arrests

In this Jan. 11, 2018 file photo, suspected members of the MS-13 gang are escorted to their arraignment in Mineola, N.Y. A sweep of alleged MS-13 gang members on Long Island has racked up impressive arrest totals but also left unanswered questions, the Associated Press reports. (AP)

“From the vicious machete attack of four young men in Central Islip, to the childhood best friends brutally murdered by MS-13 in Brentwood, our community has witnessed the indiscriminate brutality of gang violence firsthand,” Zeldin, who met with Trump recently to discuss the issue, said in a statement obtained by Fox News. “United States naturalization is a privilege not a right, and those who have had this privilege bestowed upon them must respect and uphold the laws of our land.”

Trump said in his State of the Union speech that federal agents have caught 220 members of MS-13 on Long Island since May, but officials are keeping a tight lid on the details of the operation, the Associated Press reported this week.

The news agency says federal and local authorities have declined repeatedly to offer specifics such as the names of those arrested and the crimes that they have committed, saying such information could jeopardize investigations and put suspects at risk.

They have only revealed that 44 arrested in the sweep, dubbed Operation Matador, have been deported.

The AP reported the secrecy comes amid accusations from immigration rights groups that innocent people are being rounded up based on unsubstantiated rumors tying them to gangs, and some detainees have even been let free by federal immigration judges after the government couldn’t prove their involvement.

Justice Department figures say the gang has 40,000 members worldwide, with around 10,000 in the U.S., carrying out crimes ranging from extortion to gun trafficking.

Trump visited Long Island in July and vowed to “dismantle, decimate and eradicate" MS-13.

"They're going to jails, and then they're going back to their country, or they're going back to their country period," he said.