The recovered black box voice recorder on the Russian Metrojet was functioning, finally affirming a week of speculation about the fate of the plane, which crashed Saturday in the Sinai Peninsula, killing all 224 people on board. As was expected, the black boxes determined it was a bombing.

Sources say the data recorder showed the flight was traveling perfectly normal and without incident for 24 minutes, then suffered a “violent and sudden explosive decompression,” breaking apart mid-air and crashing into a mountainous part of the peninsula.

The audio recorders also picked up the sound of the explosion, apparently a bomb, as investigators say the explosion was not consistent with engine failure or any other technical problem. Russian experts have taken samples from the plane and are still looking for traces of explosives.

The ISIS affiliate in the Sinai Peninsula claimed credit for downing the plane on the day of the crash, and intelligence has since suggested that an airport employee at the Sharm el-Sheikh airport planted the bomb on the plane before takeoff.

Early in the week, most officials on all sides were doubting the ISIS story. It’s not surprising, as ISIS did not offer any details on how they carried out such an attack. This led many at the time to suspect that ISIS was simply claiming credit for a random crash.

Yet US and British intelligence started picking up communications from ISIS suggesting that they indeed did have something to do with it in the days that followed, and Russia followed their lead today, announcing they are halting all flights out of Egypt for security’s sake.

The Egyptian junta, by contrast, has repeatedly denied that ISIS was responsible for the attack, and has slammed the nations that have halted flights to the peninsula as buying into “propaganda.” Tourism is economically important to Egypt, and the junta is rejecting calls to ratchet up security at Sharm el-Sheikh resort, insisting they have the situation well in hand.