Five days after the tragic crash of EgyptAir Flight 804 that took the lives of 66 passengers and crews , terrorist groups remain to be mum.

The silence of the terrorist groups who would immediately claim responsibilities over their attacks has now brought the authorities to suspecting a possibility of more disturbing reasons behind the tragedy.

Daveed Gartenstein-Ross, Georgetown University terrorism expert, believes on the possibility that terrorist groups may choose to remain silent over the tragedy should they wish to use the same method again. The said leeway has also been brought into consideration by other agencies involved in the investigation over the crash.

There can also be a possibility that terrorist groups are protecting their operatives who are in danger of being arrested should they decide to admit that it was their attack that the brought EgyptAir Flight 804 down, as per FT Com.

"The bombing of Philippines Airlines Flight 434 in December 1994 was not claimed because the planners hoped to use an improved version of the same device in a larger attack targeting 10 trans-Pacific airliners," said Scott Stewart, vice president of tactical analysis at research firm Stratfor, according to CNBC.

Terrorist groups' five days of silence may also be considered too early to confirm their innocence over the matter as it took one year before Al-Qaeda to claim responsibility for the Paris, London attack killing over 130 people.

The Telegraph reported that all the authorities have right now are the data they managed to gather from Flight 804's Ascar system that sent a transmission on the ground. The transmission indicated the presence of smoke before the aircraft completely lost contact.

This data, however, does not answer all of the questions regarding the tragedy. Investigators are still waiting for the recovery of the plane's black box which can clearly reveal what actually happened moments before the crash.

Watch this video for some of the footages on the accident.