The momentum to bring peace to Syria built up after the Paris attacks, went up in smoke on Tuesday when Turkish military shot down a Russian fighter jet, believed to have strayed into Turkey's airspace.
From that moment, François Hollande's uphill battle to get Russia on board a grand anti-IS coalition got just that little bit steeper. So much so, that it now seems like an impossible equation to solve.
"I will tell him [Vladimir Putin] that we should all be fighting against the Islamic State, and that we should deploy all of our resources to eradicate this group and better coordinate our action," Hollande said on Wednesday night following a meeting with German Chancellor Angela Merkel, as part of his frantic diplomatic marathon.
If the French President had to remind Russia who it should be fighting, it means clearly they're not on the same page.
"I think the first order of priority for Hollande is to convince Russia to go in a bigger way against ISIL and not just against rebels in Western Syria, which was their first priority target until now," explains Marc Pierini, a former EU diplomat and visiting scholar at Carnegie Europe.
Turkey has repeatedly accused Russia of targeting all positions in Syria except those held by IS, whilst Russia accuses Turkey of "complicity with terrorists", Putin said earlier this week
The two countries already at loggerheads over the Syrian conflict, were reminded just how much they don't see eye to eye after they failed to agree on whether the downed Russian jet actually violated Turkish's airspace or not.
"The recent incident with the Russian aircraft in Turkey, shows that the different participants of this coalition have severe differences and purposes of this coalition," Russian expert Nade’zhda Uzunova from the Russian Institute for Strategic Studies in Moscow, told RFI.
Downed jet exposes cracks in alliance
Ankara seeks Syrian leader Bachar Al Assad's overthrow, whilst Moscow is doing everything to keep him in power. It's an unsolvable equation. But it's not the priority right now, says Pierini.
"We have to in a way agree that the fate of Bashar Al Assad himself and his entourage is not a priority in time, so not now, but it remains a problem for the entire Western coalition... so it's a problem to be discussed later,'" he said.
One of Hollande's most immediate wishes is trying to seal the porous border between Turkey and Syria, which seems to have been a route followed by many Islamic State fighters. This move has already been backed by Russian Foreign Minister Sergei Lavrov.
If the borders are closed, it will stop what certain analysts claim is funding to Islamic State: "Turkey needs to stop letting convoys of smuggled oil enter into Turkey!" Pierini insisted.
President Recep Tayyip Erdogan has vigourously denied claims that Turkey buys any oil from the Islamic State group, insisting his country's fight against the jihadists was "undisputed".
Undisputed or not, the NATO member's allies are skeptical about Turkey's real endgame, which doesn't bode well if they're all to get into bed together. Trust like in any marriage is essential. Without it there can be no harmony.
Yet Uzunova thinks that Russia can still come on board despite its fallout with Turkey, given its past traumas with terrorism.
“Russia is one of those countries who struggle from terrorism very much, so the Russians are very interested to fight with Daesh, and you know the terrorist attacks which took place in Paris, touched Russians very much after a Russian aircraft crashed in Egypt, it was a very strong emotion,” she said.
In the end, it's perhaps less Islamic State and more trauma that is the common bond, and it's that which may help Hollande seal his deal with Putin.