US House Homeland Security Committee Chairman Mike McCaul (R-TX) has reiterated that a biometric entry-exit system is vital for the US preventing terror attacks.Speaking at a hearing on terror exploitation of the US refugee and visa process, McCaul noted that in previous attacks such as 9/11, that some of the perpetrators were in the US on overstayed visas.”Terrorists have used student visas, tourist visas, and more to infiltrate our country and plot significant acts of terrorߪThis is why we must fulfill one of the last remaining recommendations of the 9/11 Commission by moving forward with a biometric entry-exit system to track those who overstay their welcome,” McCaul said.In late January, a Senate panel said the implementation of a biometric exit tracking system is a priority for national security.In response, Rebecca Gambler with the Government Accountability Office stressed that challenges confronted the agency in terms of choosing the best biometric modality and collection method. John Wagner, deputy assistant commissioner at Customs and Border Protection, also explained different scenarios to show the difficulty of tracking passengers in different environments.A bill being proposed by Reps. Richard Hudson, R-N.C., and Michael McCaul, R-Texas would put pressure on federal security and intelligence officials to change the vetting process for all refugees entering the country.