Now the leaders of Britain, Russia and Egypt are openly disagreeing about the cause.

　　DAVID CAMERON, Prime Minister, United Kingdom: We cannot be certain that the Russian airliner was brought down by a terrorist bomb. But it looks increasingly likely that that was the case.

　　HARI SREENIVASAN: British Prime Minister David Cameron spent the day defending his decision to stop all British flights to and from Sharm el-Sheikh in Egypt, pending the crash investigation.

　　DAVID CAMERON: The reason we have acted before that is because of the intelligence and information we had that gave us the concern that it was more likely than not it was a terrorist bomb.

　　HARI SREENIVASAN: Russian officials insisted any talk that a bomb destroyed the Metrojet airliner is just speculation. And the Russian Foreign Ministry urged Britain to share any intelligence it has.

　　MARIA ZAKHAROVA, Russian Foreign Ministry Spokesperson (through interpreter): Honestly, what's really shocking is the realization that the British government has some kind of information that could shed light on what happened in the skies above Egypt. That information, if it exists, and judging by the fact that the head of the Foreign Office pronounced it does exist, that information was never shared with the Russian side.

　　HARI SREENIVASAN: The Kremlin said President Vladimir Putin raised those concerns in a phone call with Prime Minister Cameron. Meanwhile, Egypt's government maintained the crash of the Russian jet — quote — “wasn't a terror act.” And under a new law, news organizations there that report anything to contrary could face hefty fines.

　　The Egyptian president, Abdel Fattah El-Sisi, was in London today to meet with Cameron. El-Sisi has warned against expecting much from the investigation anytime soon. But he said British security teams checked Sharm el-Sheikh's airport 10 months ago and would be welcome to do so again.

　　PRESIDENT ABDEL FATTAH EL-SISI, Egypt (through interpreter): I understand that the prime minister wants to be assured of his citizens' well-being. This is his right. We're prepared to cooperate further with any procedures that reassure all our friends that the security measures in place at Sharm el-Sheikh airport are enough and that the airport is safe to a good standard.

　　HARI SREENIVASAN: Stepped-up security screenings were in evidence at the Red Sea resort's airport today. Thousands of tourists remained stranded there, after Ireland, Germany and the Netherlands followed Britain's lead and also suspended their flights. Later, British carriers Monarch and EasyJet announced they will begin evacuation flights to Sharm el-Sheikh tomorrow with official approval to bring the vacationers home. That process could take up to 10 days.

　　In Washington, President Obama said U.S. officials are taking — quote — “very seriously” the possibility that a bomb destroyed the Russian plane.