(Reuters) - A scant 35 people were taken into custody during a long-threatened U.S. enforcement action that targeted more than 2,100 immigrants who had been ordered deported, the head of U.S. Immigration and Customs Enforcement said on Tuesday.

President Donald Trump described the action over the July 13 weekend, dubbed “Operation Border Resolve,” as “very successful” even though much of the activity was not visible to the public.

The operation was originally scheduled for June for a dozen major U.S. cities and was highly publicized, which likely contributed to the low rate of arrests, acting director of ICE Matthew Albence said on a call with reporters.

He described the operation as targeted against specific individuals who were in violation of the law, not raids.

“I guarantee you if we were doing raids, and we had officers running all over the place picking up targets indiscriminately, you would have videos all over YouTube,” he said.

As word spread about the possible ICE operation, immigration rights groups circulated “know your rights” materials in immigrant communities and local activists advised people not to answer the door to agents without a warrant.

Albence said some operations were called off because their officers were “under surveillance.”

Trump signaled the impending enforcement in a June tweet, saying officials would soon “begin the process of removing the millions of illegal aliens who have illicitly found their way into the United States.”

Albence skirted a question about the president’s tweets, blaming media coverage in general and said past operations had been more successful in part because they were carried out with less attention.

He also said more than 3,000 businesses were notified by ICE that they will be audited and could face criminal charges stemming from employment of illegal immigrants.

Facing a re-election battle next year, Trump has wanted to show his supporters that he is delivering on campaign promises to crack down on illegal immigration, a signature policy objective of his administration.

He has pushed Guatemala, Mexico and other countries in the region to act as buffer zones and take in asylum seekers who would otherwise go to the United States.

Trump wrote on Twitter on Tuesday that he is now considering a “ban,” tariffs and remittance fees after Guatemala decided to not move forward with a safe-third-country agreement that would have required the Central American nation to take in more asylum seekers.

It was not immediately clear what policies he was referring to. The White House and the Guatemalan government did not immediately respond to requests for comment.