The sight of Russia's Foreign Minister standing alongside the US Secretary of State, announcing an agreement over the future of Syria, will have delighted President Vladimir Putin.
By hurling Russian military might into Bashar al-Assad's struggle against his people, Putin has seized the ability to bargain on equal terms with America on the most urgent crisis in the Middle East. That alone will have justified the Geneva agreement in Putin's eyes.
But will the deal work? The accord that emerged from countless hours of talks between Kerry and his Russian counterpart, Sergei Lavrov, can be summarised as follows. If Assad's regime and his Russian allies will observe a ceasefire for seven days and allow the United Nations to dispatch aid convoys to besieged areas, then the Kremlin will be rewarded with military cooperation with the US.
In fact, Washington will open new vistas of battlefield intelligence. The US will tell Russia - and, by extension, Assad - what it knows about the precise locations of Jabhat Fateh al-Sham, once known as Jabhat al-Nusra, the branch of al-Qaeda in Syria, together with the positions held by "moderate" rebels.
In theory, this will allow Russia and the US to carry out coordinated air strikes against the former group while protecting the latter. But who can tell how that vital information, once handed over, might be used in future?