Marco Rubio was going to secure a deal for President Donald Trump"even if it meant betraying U.S. informants.

The secretary of state made a secret agreement with the president of El Salvador to hand over legally protected U.S. "informants," so the Trump administration could deport hundreds of Venezuelan immigrants to a notorious prison in the country, a new Washington Post report revealed on Sunday.

The backroom deal, officials told the Post, undermined years of work from an ongoing U.S. investigation aimed at apprehending high-ranking members of MS-13, one of the world's most violent gangs, whose acts of brutality have been on display in the U.S. and beyond.

"The deal is a deep betrayal of U.S. law enforcement, whose agents risked their lives to apprehend the gang members," Douglas Farah, a U.S. contractor who worked with federal officials to investigate and help dismantle the MS-13 gang, told the outlet.