Mr Lavrov may be disappointed if he studies the text of the JCPOA itself. Baked into the deal in the form of the dispute settlement process was an automatic snap back of UN sanctions in the event of any dispute about compliance - even if the dispute was about US compliance.

There is no blocking vote available to Russia and China. The JCPOA is clear: in the event of the reference of any dispute to the Security Council, absent a positive vote to continue UN sanctions relief (and subject therefore to a veto from the US) the old UN sanctions regime falls back into place.

Ironically perhaps, the Obama administration negotiated terms that in theory enable President Trump to repudiate the JCPOA and which leave Iran with few alternatives but for an automatic snap back of UN sanctions. But that is not to say Iran has no options at all. The staggering of the waivers of US secondary sanctions mean there is scope for some diplomatic maneuvering for both sides. There is plenty left to play for yet.