The Obama administration has declared the ultra-violent street gang MS-13 to be an international criminal group, an unprecedented crackdown targeting the finances of a sprawling US and Central American crime group.
MS-13, or Mara Salvatrucham, is infamous for hacking and stabbing victims with machetes.
The Treasury Department formally designated MS-13 a transnational criminal organisation. The aim is to freeze it out of the US financial system and seize what are estimated to be millions of dollars in criminal profits from drug and human smuggling and other crimes committed in the US.
The gang was founded by immigrants fleeing El Salvador's civil war more than two decades ago. Its founders took lessons from that brutal conflict to the streets of Los Angeles and built a reputation as one of the most ruthless and sophisticated street gangs, according to Immigration and Customs Enforcement (ICE).
With as many as 10,000 members in 46 states, the gang has expanded far beyond its roots. Members are accused of major crimes including murder, kidnapping, prostitution, drug smuggling and human trafficking.
The group established itself in Los Angeles before spreading across the US, said Jason Shatarsky, an MS-13 expert assigned to ICE's national gang unit. The group's violence surprised authorities and even rival gangs.
"They saw a level of violence that hadn't been seen before," Mr Shatarsky said, adding that as the gang has expanded it has also become more sophisticated than many rivals.
The gang, which is allied with several of Mexico's warring drug cartels, has a strong presence in southern California, Washington and northern Virginia, all areas with substantial Salvadoran populations.
Mr Shatarsky said its members target residents and business owners for extortion, among other crimes. The gang is also active throughout Central America and in parts of Mexico. Authorities in Europe have reported evidence of MS-13 expanding operations there.
By labelling MS-13 an international criminal organisation subject to sanctions by the Treasury Department's Office of Foreign Assets Control, the government hopes to stymie the gang's ability to funnel money back to its leaders in El Salvador or launder criminal proceeds through otherwise legitimate businesses.