From AviationSafety.Net:
The United States FAA issued a Notam, warning U.S. airlines to avoid flying below FL260 over the Egypt Sinai Peninsula due to security concerns.
The FAA states that international civil air routes that transit the Cairo (HECC) Flight Information Region (FIR) over the Sinai Peninsula and aircraft operating to and from Sinai airports are at risk from potential extremist attacks involving antiaircraft weapons, to include Man-Portable Air Defense Systems (MANPADS), small arms fire, and indirect fire from mortars and rockets targeting Sinai airports. Some of these weapons have the capability to target aircraft at high altitudes and/or upon approach and departure. The militant group Ansar Bait al-Maqdis (ABM) has shot down an Egyptian Mi-17 military helicopter flying at low altitude using MANPADS, in January 2014. Although MANPADS have not been used to target civil aircraft in the Sinai, they could be used to potentially engage civil aviation. Attacks against aircraft in-flight or weapons fire targeting Sinai airports can occur with little or no warning.
Based on this information, the FAA advises airlines and operators to avoid flying below FL260 in this area.
The European Aviation Safety Agency (EASA) issued a similar warning in November 2014, recommending all operators to take any available information into account in their risk assessments and routeing decisions if planning to fly into, out of, within or over the North Sinai Governorate of Egypt and to monitor all relevant information, including NOTAMs.
Current notam
1A6349
HECC CAIRO FIR -——————————1A6349/15 SECURITY EGYPT, NORTHERN SINAI PENINSULA, POTENTIALLY HAZARDOUS SITUATION
CONTENT: GERMANY ADVISES ALL GERMAN OPERATORS NOT TO PLAN AND CONDUCT FLIGHTS BELOW FL260 DUE TO HAZARDOUS SITUATION IN THE AIRSPACE OF EGYPT, REGION NORTHERN SINAI (FIR CAIRO).
POTENTIAL RISK TO AVIATION OVERFLYING THIS AREA BELOW FL260 AND TAKE OFF / LANDING AT ALL AIRPORTS FROM DEDICATED ANTI-AVIATION AND GROUND TO GROUND WEAPONRY.
OPERATORS ARE STRONGLY ADVISED TO TAKE POTENTIAL RISK INTO ACCOUNT IN THEIR RISK ASSESSMENT AND ROUTEING DECISION. AFFECTED AREA: AREA WITHIN N311400E322200 - N294000E324000 - N293000E345400 N312000E341200 - N311400E322200
EMERGENCY SITUATIONS:
IN AN EMERGENCY THAT REQUIRES IMMEDIATE DECISION AND ACTION FOR THE SAFETY OF THE FLIGHT, THE PILOT IN COMMAND MAY DEVIATE FROM THIS NOTAM TO THE EXTENT REQUIRED BY THAT EMERGENCY.
FL260 = 26,000 feet