President Donald Trump on Tuesday cited the recent apprehension of ten suspected terrorists to bolster his case for building a wall along the southern border, implying that a porous border with Mexico is leaving the country vulnerable to national security threats.

But the Department of Homeland Security, which oversees security and law enforcement at U.S. borders and ports of entry, was unable to provide data to directly substantiate that claim.

Instead, DHS would only say that it apprehended, on average, ten “known or suspect[ed] terrorists” per day who attempted to enter the country “by air, sea, or land” from October 2017 through September 2018.

“These are individuals that hit against U.S. terror watchlists,” the statement read. “This is in addition to the 17,000 criminals and 3,000 special interest aliens that CBP apprehended at the border last year.”

Asked to clarify whether ten of those recent arrests occurred on the southern border, as the president claimed, DHS simply reiterated its per-day statistic for the year.

The issue over the national security threat posed at the southern border came up in an Oval Office meeting between president, House Minority Leader Nancy Pelosi (D-CA), and Senate Minority Leader Chuck Schumer (D-NY), during which Trump demanded that $5 billion in border wall funding be included in any government funding deal.

“People are pouring into our country, including terrorists,” the president said at one point. “We caught ten terrorists over a short period of time. These are serious people. All of our law enforcement have been incredible, but we caught ten terrorists, people looking to do harm. We need the wall.”

A request for comment made to the White House was not immediately returned. But data from the State Department shows that in 2017, “there was no credible evidence indicating that international terrorist groups... sent operatives via Mexico into the United States.”

At the same time, State warned that the threat of such entry persists. “The U.S. southern border remains vulnerable to potential terrorist transit, although terrorist groups likely seek other means of trying to enter the United States,” the department wrote.

Additional government data indicate that border security is indeed a terrorism issue, but that those on the terrorism watchlist come from the north, not the south. FBI reports from 2014 through 2016 suggest far more attempted terrorist incursions from Canada than Mexico. In the end, the main threat, terrorism experts argue, are individuals already in the country who have become radicalized.

"Every objective analysis has reflected that the primary terrorism threat taking place today is from those who are born here and are native to the U.S.,” said John Cohen, the former deputy under secretary for intelligence and analysis at DHS. “If the president is saying that 10 documented and known terrorists were captured at the border recently, if that were true, it would be significant. But I’m skeptical of that claim.”

Cohen said that in order for the U.S. government to stop known or suspected terrorists from entering the country, they would first have to apprehend and detain them for questioning. At that time, Customs and Border Protection officers would take fingerprints and other biometric data to identify the individual and bounce that information off of U.S. intelligence databases. Cohen also said that the U.S. could be cooperating with Mexico to identify individuals with ties to terrorism.

Members of the DHS advisory council confirmed to The Daily Beast that they are headed to the border next week to meet with officials and to collect data on those who have been apprehended at the border this year. The group will fly into California before heading to Texas.

With reporting by Asawin Suebsaeng