In the days leading up to President Donald Trump's televised address to the nation Tuesday night to promote his southern border wall, administration officials justified the proposal by claiming that thousands of terrorists pour across that border.

Data and analysis from Trump's own administration drastically undercut that message, calling into question whether the situation along the U.S.-Mexican border is truly a "national emergency" as Trump said.

White House spokeswoman Sarah Sanders said Friday that Customs and Border Protection officials caught nearly 4,000 known or suspected terrorists "that came across our southern border." She repeated that on talk shows throughout the weekend, and Vice President Mike Pence used the same data point during an appearance on "Good Morning America" on Tuesday.

But in the State Department's summary of global terrorism threats published in September, analysts concluded there was "no credible evidence indicating that international terrorist groups ... sent operatives via Mexico into the United States."

Monday, NBC News reported that the number of known or suspected terrorists caught along the southern border in the first half of 2018 was about 1 percent of the Trump administration's claim. According to Customs and Border Protection data provided to Congress, the agency encountered 41 people on the Terrorist Screening Database from Oct. 1, 2017, to March 31, 2018, along the U.S.-Mexican border. Thirty-five of them were American citizens or lawful permanent residents, and only six were classified as non-U.S. persons.

Monday night, White House adviser Kellyanne Conway acknowledged in an appearance on Fox News that Sanders conflated two very different statistics while trying to make her argument. In fiscal year 2017, federal officials stopped 3,755 people on the terrorist watch list from traveling to or entering the USA, but that includes people traveling through airports, seaports and land ports. The majority of those tried to enter by air.

"That was an unfortunate misstatement," Conway said. "Everybody makes mistakes, all of us. The fact is, it's corrected here."

In a statement Monday, Department of Homeland Security Secretary Kirstjen Nielsen said she did not provide an exact number of how many of those on the terrorist watch list were stopped at the southern border, saying it was “sensitive” and could not publicly be released. Homeland Security did not dispute the accuracy of the NBC News report that found 41 known or suspected terrorists were caught there.

As criticism of their terrorism statistics increased, administration officials started using another metric to warn of potential dangers crossing the border.

In 2018, agents encountered more than 3,000 "special interest aliens" at the southern border. That is a loose definition that does not indicate any kind of specific intelligence on that person, only that he or she has traveled to or come from 35 countries considered to be of "special interest" after the Sept. 11 terrorist attacks because of their historic ties to terrorism.

Nielsen cited those "special interest" people Monday in a series of tweets warning, "The threat is real."

In a statement after those tweets, Nielsen made clear that being designated a "special interest alien" does not mean the person is a national security threat.

"This does not mean that all (special interest aliens) are 'terrorists,' but rather that the travel and behavior of such individuals indicates a possible nexus to nefarious activity (including terrorism) and, at a minimum, provides indicators that necessitate heightened screening and further investigation," she wrote. "The term (special interest alien) does not indicate any specific derogatory information about the individual – and DHS has never indicated that the (special interest alien) designation means more than that."