Censor.NET reports citing The New York Times.
First, Mr. Putin said the Russian Air Force's bombing campaign in Syria was partly intended to help dismantle the Islamic State, also known as ISIS or ISIL, which includes up to 7,000 fighters from Russia and the former Soviet Union. One worry is that they might return to wage a terrorist war in Russia. An attack against a civilian airliner would confirm that Russian interests were already being threatened - and might cause Russia to begin targeting the Islamic State more aggressively.
Second, Mr. Putin's Syrian intervention has been taken as an attempt to show that Russia is again become a global power capable of tackling the world's most intractable problems. Reversing course after the first setback, however violent, would undercut that image.
Third, the Russian leader has painted the West, and the United States in particular, as quick to abandon its Arab allies since the dawn of the Arab Spring in 2011 and its chaotic aftermath. Syria, now beleaguered, has been Russia's only Arab ally for decades, but Mr. Putin has also been courting President Abdel Fattah el-Sisi of Egypt. A terrorist attack by enemies of the Egyptian government will most likely strengthen, not diminish, that effort.
Alexei Makarkin, an analyst at the Center for Political Technologies, saw two main options for Russia. One, he said, was that "Russia can intensify the Syria operation, send more troops and volunteers to support Assad." That move, he said, would probably worsen already strained ties with the West.
In the second option, "Fighting the Islamic State will become a priority rather than supporting Assad," he said. "In this situation, Russia will pressure Assad to move toward a transitional government."
Other analysts said that the slow Kremlin reaction compared with other governments' responses reflected both Mr. Putin's own caution and the desire not to harm Egypt: Russians make up about a third of the nine million tourists who visit the country annually. Almost 80,000 still need to be flown home, government officials said. "It is important for Russia to be seen in the Middle East to be in close touch with the biggest Arab country," said Dimitri Trenin of the Carnegie Moscow Center.