Obama, the DemoRat party and their "Arab Spring" "democracy" movement that ousted a stable and legal Mubarak Presidency.
The US Government supported (in Egypt) Muslim Brotherhood (al Qaeda), and the terrorist criminal Morsi (Obama's hand picked puppet).
The thousands of convicted MB terrorists in Egyptian prisons, and the US Government agents in Egypt working to bring down al Sisi and the current Egyptian Government.
The Muslim Brotherhood operatives and the US Government agents have the means, motive and opportunity to place a sophisticated, difficult to detect, bomb on any airliner that leaves Egypt.
This is a great embarrassment to Putin and I doubt he’s going to let it stand. If terrorism, you can expect what’s happened so far to be foreplay. This ISIS group in Egypt should be child’s play.