Read: Preparing for War, page-20

GZ. It was Israel because it is denied by everyone else in the vicinity with missiles. From the British Forces Network:

"The Syrian Central Media run by the government said the missiles targeted Shayrat air base in Homs."

https://www.forces.net/news/syria-air-defences-shoot-down-missiles-state-tv-reports

They would not quote Assad's media if the facts were debatable.

And so we have Iran, Israel and Turkey all operating autonomously and to their own agendas. Putin will see the risks here but how he grades those risks may be a tad different my rudimentary analysis (or should I say instinct).

On the other hand Putin can only predict the likely actions and responses of Iran and perhaps France & Israel.

There isn't a person on this planet who can predict Erdogan's next backflip or Trump's next tweet. In other words Putin needs to co-ordinate with the US through France and bring Iran into it.