In response to last month’s foiled bomb plot against the U.S. Capitol, the House Homeland Security Committee’s Subcommittee on Border and Maritime Security held a hearing to examine the national security implications of immigrants who overstay their visas. The suspect in last month’s plot, Amine el-Khalifi, is a Moroccan national who had been in the United States illegally for more than a decade. As the Associated Press reports, the government has failed to track millions of foreign visitors who outstay their visas.

FOX reports that during the hearing, Deputy Counterterrorism Coordinator John Cohen said DHS is planning to implement a biometric tracking system that will monitor when immigrants leave the country.