French President Franç ois Hollande traveled to Moscow on Thursday to meet with Russian President Vladimir Putin , following a week of intense diplomacy to form a grand coalition against Islamic State.

On the agenda: The multidimensional conflict in Syria and efforts to coordinate the fight against Islamic State. Messrs. Putin and Hollande have called for a broad international coalition to fight the Sunni extremist group, but have offered little clarity on how more countries can cooperate.

"We must build this broad coalition I've spoken of to strike this terrorism," Mr. Hollande said in remarks carried on Russian state television. "I'm in Moscow with you to see how we can act and coordinate so that we can strike this terrorist group and find a political solution for Syria."

Mr. Putin noted Mr. Hollande's efforts to create a broad coalition to fight Islamic State, adding: "You know our position. We are prepared for such joint work, consider it necessary, and in that regard our positions coincide."

But efforts to strengthen cooperation between Russia and the West were put in serious peril on Tuesday, after a Turkish fighter plane shot down a Russian warplane that had been flying a strike mission over Syria, touching off a major diplomatic crisis and threatening a breakdown in relations between the Kremlin and North Atlantic Treaty Organization member Turkey.

"The whole discussion will be very much influenced by the events of the last 48 hours," a Western official said. "The real factor is that you cannot disregard Turkey when it comes to talking about the fight against Daesh," the official said, using another name for Islamic State.

Also unclear is whether the budding alliance will narrow differences between the Kremlin and the West over the future of Syrian President Bashar al-Assad.

After meeting with U.S. President Barack Obama on Tuesday, Mr. Hollande repeated that Syrian President Bashar al-Assad must step down as part of a peaceful solution. Mr. Putin, however, has continued to back the Syrian leader.

Still, French officials say the parameters have shifted, even if Paris' hard line on Mr. Assad remains intact. That means the Syrian president could be part of a political transition, although not the solution.

The Russian military launched an aerial bombardment campaign in Syria on Sept. 30, lending crucial support to Syrian government forces. Mr. Putin cast Russia's air war as a fight against Islamic State, calling for other nations to join his antiterror coalition. But the U.S. and its allies said Russia's military intervention was largely focused on other, mostly Sunni rebel groups arrayed against Mr. Assad, not Islamic State. Mr. Putin's alliance includes Shiite theocracy Iran, Shiite-dominated Iraq and the Syrian government, which draws core support from the Shiite-linked Alawite sect

The Moscow leg of Mr. Hollande's diplomatic marathon will be the toughest test of the French leader's effort to build an alliance to fight Islamic State.

In the immediate aftermath of the Paris attacks, Mr. Hollande called for a "grand, single coalition" to bombard Islamic State. But diplomats in Paris have since rowed back from that vocabulary as they acknowledge the impossibility of Russia and the U.S. working in a formal military coalition.

With Russia, French officials talk of strengthening cooperation and coordination, and looking for "synergies" with Russian strikes in Syria. For example, if France targets an oil depot in a raid, Russian strikes on moving oil trucks can provide a useful reinforcement, one French diplomat said.

"It's about ensuring a better exchange of information so that strikes are more effective," the diplomat said.

When Mr. Hollande sits down with Mr. Putin, he will also have to navigate divisions over a political solution in Syria.

"It's a question of putting all our cards on the table, not of resetting relations," a second French diplomat said ahead of the meeting between Mr. Hollande and Mr. Putin. "We don't want Russia on one side and us on the other; that would be explosive."

Write to Nathan Hodge at nathan.hodge@wsj.com and William Horobin at William.Horobin@wsj.com

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(END) Dow Jones Newswires

November 26, 2015 19:45 ET (00:45 GMT)