Some 20 delegations gathered for a second round of talks on Syria's nearly five-year conflict that has left 250,000 dead, sparked a refugee crisis in Europe and birthed the Islamic State group that has terrorised many nations at the table.
Paris became the latest victim of the snowball effect of Syria's conflict with a series of attacks last night that left almost 130 people dead at the hands of gunmen who blamed their actions on French military action in Syria.
He said France had ordered security stepped up at embassies and official buildings around the world as he rushed back to his traumatised country after only a few hours in Vienna.
Russian Foreign Minister Sergei Lavrov agreed, saying that the attacks were "no justification" to ease up on tackling radical jihadists such as IS and the Al-Nusra Front, affiliated to Al-Qaeda.
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And US Secretary of State John Kerry said that the attacks will "stiffen our resolve, all of us, to fight back."
EU foreign policy chief Federica Mogherini said that the bloodbath added "another kind of meaning" to the gathering.
"The countries sitting around the table have almost all experienced the same pain, the same terror," she said, citing the recent Russian plane disaster in Egypt and suicide bombings in Beirut and Turkey.
In almost five years, fighting between the regime of Syrian President Bashar al-Assad and rebel groups as well as IS militants has killed over 250,000 people and forced millions into exile, leaving many of them stranded in neighbouring states.
The Paris attacks threw into stark relief the need to resolve the Syrian conflict, but also how complex a task that is.