President Donald Trump said on Tuesday that he had no proof there were “Middle Easterners” among a caravan of migrants headed to the US from Central America.

Trump had claimed on Monday that “criminals and unknown Middle Easterners” were “mixed in” with the caravan, with Vice President Mike Pence later echoing his assertions in a live interview.

An estimated 7,200 migrants from Latin America are headed toward the US, fleeing rampant poverty and violence in their home countries. They had reached Huixtla, Mexico, as of Tuesday.

President Donald Trump said during a Tuesday-afternoon press conference that he had no proof to back up his and Vice President Mike Pence’s repeated assertions that “unknown Middle Easterners” were among a caravan of migrants heading to the US from Central America.

Trump said “there’s no proof of anything, but there could very well be” when pressed by CNN reporter Jim Acosta for concrete evidence that people of Middle Eastern descent or that suspected terrorists were among the group.

After initially tweeting that claim on Monday that “criminals and unknown Middle Easterners” were “mixed in” among the estimated 7,000 migrants headed to the US, Trump doubled down later that day, telling reporters “if take your cameras and search … you’re gonna find MS-13, you’re gonna find Middle Eastern, you’re gonna find everything.”

In a Monday interview with The Washington Post’s Robert Costa, Vice President Mike Pence echoed Trump, calling it “inconceivable there are not people of Middle Eastern descent in a crowd of more than 7,000 people advancing toward our border.”

Trump’s denial came after White House press secretary Sarah Sanders said Trump “absolutely” had proof of Middle Eastern people in the caravan, with both Sanders and Pence’s spokeswoman, Alyssa Farah, emphasizing Department of Homeland Security statistics stating that an average of 10 “suspected terrorists” a day were apprehended by Border Patrol in 2017.

The migrants in the caravan are mainly fleeing El Salvador, Honduras, and Guatemala, three nations riddled with gang violence, corruption, and poor economic conditions, to immigrate or seek asylum in the US. As of Tuesday, they had reached the city of Huixtla, Mexico, about 1,100 miles from the US border.