CAIRO • In an eerie coincidence, the EgyptAir jet that plunged into the Mediterranean was once the target of political vandals who wrote in Arabic on its underside, "We will bring this plane down".

Three EgyptAir security officials said the graffiti that appeared about two years ago had been the work of aviation workers at Cairo Airport. Playing on the phonetic similarity between the last two letters in the plane's registration, SU-GCC, and the surname of President Abdel-Fattah el-Sissi, some workers also wrote "traitor" and "murderer".

The officials, who spoke on condition of anonymity because they were not authorised to speak publicly, said the graffiti had been linked to the domestic Egyptian political situation at the time rather than to a militant threat. Similar graffiti against the former general was scrawled across Cairo after the military ousted elected former president Mohamed Mursi in 2013.

Since then, the airline has adopted new security measures in response to Egypt's political turmoil, extremist violence and other aviation disasters, such as the Russian plane crash that killed 224 people last October. EgyptAir has fired employees for their political leanings, stepped up crew searches and added unarmed in-flight security guards. Three such guards died in last Thursday's crash of Flight MS804.

Whether those moves are sufficient remain an open question as experts study data transmitted by the plane in its final minutes for clues as to what brought it down.

EgyptAir's security procedures last came under scrutiny in March when a passenger on a domestic flight pretended to be wearing an explosive vest and forced the plane to land in Cyprus. The crisis was resolved within hours when the man, later determined to be psychologically troubled, surrendered.

NEW YORK TIMES