The Federal Aviation Administration issued unexplained notices late Tuesday closing airspace over El Paso and a large patch of southern New Mexico west of Santa Teresa for 10 days. El Paso International Airport is closed to all flights, the city said.

The orders close off all air travel in the affected area, which could cause massive disruption in the nation's 23rd largest city.

"THE FEDERAL AVIATION ADMINISTRATION (FAA) CLASSIFIES THE AIRSPACE DEFINED IN THIS NOTAM AS 'NTL DEFENSE AIRSPACE'. PILOTS WHO DO NOT ADHERE TO THE FOLLOWING PROC MAY BE INTERCEPTED, DETAINED AND INTERVIEWED BY LAW ENFORCEMENT/SECURITY PERSONNEL," the notices said.

"THE UNITED STATES GOVERNMENT MAY USE DEADLY FORCE AGAINST THE AIRBORNE ACFT, IF IT IS DETERMINED THAT THE ACFT POSES AN IMMINENT SECURITY THREAT," the notice continued.