There is the Convention on Cluster Munitions, which bans cluster bombing outright, but conveniently neither Russia or Syria signed it.
Even if they did, international treaties/law banning weapons tend to go out the window in times of war. Take white phosphorus for example, which is banned by the Convention on Certain Conventional Weapons for use as an incendiary weapon but has reportedly used by the US, Israel, Ukraine, Armenia, Taliban and Iraq under Saddam Hussein for such purpose.
Even if they did, international treaties/law banning weapons tend to go out the window in times of war. Take white phosphorus for example, which is banned by the Convention on Certain Conventional Weapons for use as an incendiary weapon but has reportedly used by the US, Israel, Ukraine, Armenia, Taliban and Iraq under Saddam Hussein for such purpose.
It's a mad world.