[WASHINGTON] France and the United States pledged on Tuesday to step up the fight against the Islamic State group, urging Russia to throw its weight behind global efforts to resolve the four-year Syrian conflict.
President Francois Hollande met his US counterpart Barack Obama at the White House as Turkey's downing of a Russian warplane dealt a severe blow to efforts to coordinate the fight against IS.
Speaking 11 days after jihadists killed 130 people in the French capital, Hollande urged an "implacable" joint response to crush the group in Syria and Iraq.
At a joint press conference, Mr Obama pledged America's full solidarity in the wake of the November 13 carnage, switching into Mr Hollande's language to tell him, "We are all French."
Washington and Paris have both stepped up their fight against IS in Syria, with France launching its first strikes from the Charles de Gaulle aircraft carrier in the Mediterranean and the US calling for more international cooperation against the jihadists.
While announcing no specific new action, Mr Hollande said he and Mr Obama agreed to "scale up our strikes both in Syria and in Iraq to broaden our scope to strengthen our intelligence sharing regarding the targets."
Both leaders said they would boost support for forces battling IS on the ground - while continuing to rule out any ground campaign.
"France will not intervene militarily on the ground," Mr Hollande said.
Illustrating the leaders' message on tighter cooperation, France said its warplanes had hit an IS command center near its key western Iraqi stronghold of Mosul, in a strike led with the US Air Force.
The talks in Washington came as Turkey's downing of a Russian warplane at the Syrian border threatened to dramatically fan tensions in the volatile region.
The most serious incident involving Russian forces since they entered the conflict in support of President Bashar Al-Assad - the downing drew a furious response from President Vladimir Putin who accused Nato-member Turkey of "a stab in the back."
Mr Obama and Mr Hollande joined UN Secretary-General Ban Ki-moon in warning against any escalation.
"Hopefully, this is a moment in which all parties can step back and make a determination as to how their interests are best served," Mr Obama said.
The US military has backed up Turkey's claim that Turkish pilots warned the Russian jet 10 times - but failed to get a response - before shooting it down.
Mr Obama said Nato ally Turkey had a right to defend its airspace - but also appealed to Russia to engage at the side of the 65 countries battling IS in Syria.
"Given Russia's military capabilities and the influence they have on the Assad regime, them cooperating would be enormously helpful in bringing about resolution of the civil war in Syria," Mr Obama said.
"If and when they do, it will make it easier for us to go after ISIL."
Both Mr Hollande and Mr Obama reiterated their determination to see Assad step down in order to give Syria a chance for peace, with Mr Hollande saying "it should be as soon as possible." "He has been the problem - he cannot be the solution," Mr Hollande said.
Mr Hollande was in Washington as part of a frantic week of shuttle diplomacy as he tries to rally global support for increased strikes against IS, which claimed the Paris attacks.
Acting on a French resolution, the UN Security Council last week authorised "all necessary measures" to fight IS.
The French leader will hold talks in Paris with German Chancellor Angela Merkel on Wednesday and with Mr Putin in Moscow on Thursday, before dining with Chinese President Xi Jinping in the French capital on Sunday.
But the delicate diplomacy around the conflict was thrown brutally off course by the fighter jet downing, as Putin warned of "serious consequences for Russian-Turkish relations."
The US government has issued a worldwide travel alert warning American citizens of "increased terrorist threats" in the wake of Islamist attacks in Paris, Mali, Turkey and elsewhere.
Police in France said they were analysing what is thought to be a suicide belt similar to those used in the Paris attacks, found without its detonator in a dustbin outside the capital.
Telephone data placed key suspect Salah Abdeslam in the area the night of the attacks.
Across the border in Belgium, Brussels entered a fourth day of lockdown over fears of an "imminent" terror strike as the manhunt continued for the Belgian-born Abdeslam.
A fourth person was charged in Belgium on Tuesday in connection with the bloodshed in Paris.
Two - Mohammed Amri, 27, and Hamza Attou, 20 - were previously charged on suspicion of helping Abdeslam escape to Brussels, while a third unnamed person faces charges of aiding him.
In France, the man who lent his apartment to the suspected attack ringleader was also charged with terror offences.
Since the attacks, French police have searched more than 1,200 premises, arresting 165 people and seizing 230 weapons - including what the interior minister called "weapons of war."