UPDATE 7:28 P.M.: Following publication of Francis Taylor's remarks, a DHS spokesperson contacted the Washington Free Beacon to clarify his comments about the exact threat ISIL poses to the southern border.
"There is no credible intelligence to suggest that there is an active plot by ISIL to attempt to cross the southern border," the DHS spokesperson said.
A senior Homeland Security (DHS) official confirmed to Congress on Wednesday that militants associated with the Islamic State of Iraq and the Levant (ISIL or ISIS) are planning to enter the United States via the porous southern border.
Francis Taylor, under secretary for intelligence and analysis at DHS, told senators during a hearing that ISIL supporters are known to be plotting ways to infiltrate the United States through the border.
"There have been Twitter, social media exchanges among ISIL adherents across the globe speaking about that as a possibility," Taylor told Sen. John McCain (R., Ariz.) in response to a question about "recent reports on Twitter and Facebook of messages that would urge infiltration into the U.S. across our southwestern border."
"Certainly any infiltration across our border would be a threat," Taylor said, explaining that border security agents are working to tighten measures that would prevent this from taking place.
"I’m satisfied we have the intelligence and the capability on our border that would prevent that activity," Taylor said.
However, McCain was dubious, referring to recent videos released by activist James O’Keefe showing him crossing the border while wearing an Osama bin Laden mask.
Asked by McCain why agents did not stop O’Keefe, Taylor could not provide an answer.
"You can’t answer it because they weren’t there to stop him," McCain responded.
"The fact is there are thousands of people who are coming across our border who are undetected and not identified, and for you to sit there and tell me that we have the capability or now have the proper protections of our southwest border, particularly in light of the urgings over Facebook and Twitter [by ISIL] for people to come across our southwestern border, is a great concern to the citizens of my state."
Taylor admitted that more must be done to shore up border security in light of ongoing threats.
"The security at the southwestern border is of great concern to the department and I certainly understand the concerns of the citizens of your state," he told McCain. "If I gave you the impression I thought the border security was what it needed to be to protect against all the risks coming across the state that’s not what I meant to say."
There is little evidence to prove that ISIL militants or other terror actors would be stopped if they attempt to cross the border, McCain said.
"I don’t think there’s any doubt, I don’t see when you look at ISIS and the growth and influence of ISIS that it would be logical [to claim they would be stopped], as they’re saying on Facebook and Twitter, to come across our southwest border because they can get across," he said.
Other U.S. officials have warned ahead of President Obama’s speech this evening that ISIL is growing in strength and seeking the capability to attack America directly.
"We remain mindful of the possibility that an ISIL-sympathizer—perhaps motivated by online propaganda—could conduct a limited, self-directed attack here at home with no warning," Matthew Olsen, director of the U.S. National Counterterrorism Center, said in a recent speech.
"We have seen ISIL use a range of media to tout its military capabilities, executions of captured soldiers, and consecutive battlefield victories," Olsen said. "More recently, the group’s supporters have sustained this momentum on social media by encouraging attacks in the U.S. and against U.S. interests in retaliation for our airstrikes. ISIL has used this propaganda campaign to draw foreign fighters to the group, including many from Western countries."