Many of the Hondurans traveling in the caravan are children, some traveling with their parents and some without, according to the documents. Because children are afforded special protections in the United States, their arrival is creating anxiety within the Trump administration, which has pledged to decrease illegal immigration. President Donald Trump said last week that he would consider separating migrant families at the border once again, after reversing his controversial “zero tolerance” policy in June.

U.S. Customs and Border Protection is tracking the caravan as the Hondurans make their way north toward the U.S. border. Meanwhile, the State Department is trying to stave off that possibility by compelling the Mexican government to stop them at its border with Guatemala.

Secretary of State Mike Pompeo will travel to Mexico to meet with his counterparts on Friday, and plans to stop the caravan will be a “prominent” topic of discussion, a senior State Department official told reporters on Wednesday.