Vladimir Putin said Moscow was ready to unite with Paris against a "mutual enemy" following the downing of the Russian airliner and the attacks in Paris.
Brussels kept subways and underground trams closed for a second day with a menace of Paris-style attacks and a missing suspect in the deadly Nov. 13 attacks in France last spotted crossing into Belgium.
France demands that its allies support the military action against the Islamic State.
The day before the Paris attacks, twin suicide bombers struck a southern Beirut suburb, killing at least 43 people, and on Friday a suicide bomber struck a funeral in Iraq, killing at least 21.
French warplanes targeted a command post and a recruitment center for jihadists in the Islamic State stronghold of Raqqa in the second consecutive night of strikes ordered by President François Hollande.
Twelve aircraft dropped 20 bombs destroying a jihadi training camp and a munitions dump in Raqqa, where Iraqi intelligence officials say the attacks on Paris were planned.