Vladimir Putin has discussed working with international "partners" to take on Islamic State militants, according to Russian media.
The Russian president was reported to have talked about the issue with his Security Council today.
Kremlin spokesman Dmitry Peskov would not say which countries Russia may be willing to work with.
Foreign Secretary Philip Hammond said the UK's decision on whether to take part in air strikes in Syria had already been made in Parliament last year and would not be "revisited":
Did Philip Hammond misspeak or did he reveal the thinking at the highest levels of government on military action in Syria?
President Obama - a leader who thought his legacy would be ending two conflicts - has plunged the US into the maelstrom of two civil wars.
A social media campaign imitating the popular Ice Bucket Challenge has gone viral. Its target is Islamic State.