A day ago there were confused signals as to the cause of the crash of the Metrojet holiday charter flight in the Sinai desert. Not any more. American and British intelligence reports are pointing to a bomb bringing down the Airbus A321 and killing all 224 people on board on Saturday more than 20 minutes after it took off from Sharm el-Sheikh for St Petersburg.

The bomb story began overnight with the UK suspending flights from the Sinai resort airport to its airports because of intelligence advice, and was followed before 7am (eastern summer time in Australia) by US reports, led by this story on CNN.

Within an hour Foreign Affairs in Canberra was advising Australians to reconsider travel plans involving Sharm el-Sheikh or, effectively, the Sinai peninsula.

The UK flight suspension and the more detailed claims made in the US reports followed, by less than a day, the left-of-field revelation by US sources that an American military surveillance satellite had detected a heat “flash” or “bloom” over the Sinai at the time and place where air-traffic control contact with Metrojet flight 9268 was lost.

These developments are of much wider concern to airlines operating flights from any country where Islamic State terrorist cells are present.

Do these developments conclusively prove that a bomb brought down the A321? Not yet. The Egypt-led crash investigation, which appears to be supported by a large and well-equipped Russian emergency response team, has the necessary material evidence at hand scattered all over the surrounding desert, where drones are being used to ensure nothing is missed.

If there was an explosion within the airframe, the unequivocal signs of this will be found in the wreckage, and its source within the jet should be determined.

A leak from the forensic team examining the bodies of the victims in St Petersburg, Russia, yesterday said those seated in the rear of the cabin had been badly burned or dismembered.

The wreckage already assembled or shown in photos at the crash site makes it unlikely a 14-year-old repair to the tail section of the A321 had failed causing the disaster, as that section of the jet doesn’t appear to have come apart.

However, even the US intelligence reports come with admitted qualifications that mean it is too early to be dogmatic about this being a terrorist bomb attack. Air crash investigations often produce surprises, uncovering factors that were not immediately apparent but had a material contribution to the outcome.

The initiation, sequence and consequences of an in-flight breakup need not involve a bomb attack, despite the intelligence concerns being quoted in the media.

The biggest effect of this disaster so far will be to raise fears of more generalised attacks on flights in the Middle East based on the capacity of terrorists to defeat security measures at airports as well as the lesser but recognised risk of ground-to-air-missile attacks in places where sophisticated weaponry is known to be in use or “at large”.