Russian President Vladimir Putin has agreed to set up a joint military operation with France to combat Islamic State.
Moscow says the move follows a telephone conversation with French President Francois Hollande, who had earlier urged the US and Russia to join a a coalition to destroy the extremist group.
He issued the call after IS admitted responsibility for the Paris attacks, which killed at least 129 people and wounded over 350.
Mr Hollande will travel to Washington and Moscow later this month to discuss ways of increasing international cooperation to smash IS and settle the Syrian crisis.
Mr Putin has apparently ordered the Russian Navy to contact its French counterparts, to work together as allies.
Russia has already joined France in launching fresh airstrikes against IS targets in its stronghold of Raqqa in Syria.
A US official said Russia was using cruise missiles launched from warships and long-range bombers in the raids.
It comes after Moscow confirmed a bomb caused the Metrojet plane crash in Egypt and offered a €47m reward for the capture of those responsible.
In a statement, France's army general staff said 10 fighter jets were involved in its latest assault on IS in Syria and that they destroyed a command and training centre.
"For the second time in 24 hours the French military conducted an air raid against Daesh in Raqqa in Syria," the statement said.
US Secretary of State John Kerry has said IS was losing territory as a result of the American-led military operations in Syria and Iraq.
He made the claim after talks in Paris with Mr Hollande about ways of strengthen their co-operation to defeat IS.
"We agreed to exchange more information and I’m convinced that over the course of the next weeks, Daesh (IS) will feel greater pressure," he said.
"They are feeling it today. They felt it yesterday. They felt it in the past weeks. We gained more territory. Daesh has less territory."
France's call for military support in Syria and Iraq has also extended to fellow EU countries.
It has invoked a never-before-used article of the EU's Lisbon Treaty which requires states to provide "aid and assistance by all the means in their power" to a member that is "the victim of armed aggression on its territory".
France's interior minister has said police carried out 128 raids across the country on Tuesday, following raids on Monday in which officers made 23 arrests and seized 31 weapons including a rocket launcher.
One of the Paris attack suspects dubbed "Public Enemy Number One" stayed at a hotel near the French capital to prepare for the massacre, it has emerged.
Syringes and pizza boxes were found in the rooms at Appart'City Paris Alfortville, where Salah Abdelam stayed with an accomplice, according to French TV station BFMTV.
An international arrest warrant has now been issued for the Brussels-born 26-year-old, described by Belgian police as "dangerous and armed".
