U.S. Homeland Security officials on Wednesday will unveil enhanced security measures for foreign flights arriving in the United States but not an immediate expansion of an in-cabin ban on laptops and other large electronic devices because they might carry bombs, sources briefed on the matter said.

The decision not to impose new restrictions on laptops is a boost to U.S. airlines, which have worried that an expansion of the ban to Europe or other locations could cause significant logistical problems and deter some travel. Airlines that failed to satisfy new security requirements could still face future in-cabin electronics restrictions, the sources said.

European and U.S. officials told Reuters that airlines have 21 days to put in place increased explosive screening and have 120 days to comply with other security measures, including enhanced screening of airline passengers.