The Trump administration blocked Major League Baseball from signing players directly from Cuba to play professionally in the U.S., nullifying a historic deal the league struck in December with the island nation’s baseball federation.

The move comes amid a broader crackdown on what the administration calls the “Troika of Tyranny”—Cuba, Venezuela and Nicaragua. The Trump administration has criticized Cuba for supporting Venezuelan dictator Nicolás Maduro, and has sought to curb some of the normalization of U.S. relations with Cuba undertaken by former President Obama.

The Obama administration previously determined that Cuba’s baseball federation was separate from the Cuban government, a key distinction that allowed MLB to negotiate the deal. Trump administration officials said Monday they were reversing that position. Therefore, MLB’s deal, which called for Cuba’s baseball federation to receive a fee for every player signed, wouldn’t be able to proceed in its current form, one administration official said.

MLB has long argued that creating a safe, legal path for Cuban players to sign with U.S. teams was a human rights issue. Players in the past have described harrowing ordeals in their efforts to escape Cuba, often with the assistance of human traffickers, and receiving death threats from smugglers seeking payment long after they arrive.

“We stand by the goal of the agreement, which is to end the human trafficking of baseball players from Cuba,” an MLB spokesman said on Monday.