The biggest player in the room is the Americans. The second-biggest is the European Union. Everyone saw the significant effects of the sanctions that came into force in April, and those were only American, right? Europe did not match those either. The European Union acting by itself can also move things, but Europe is 28 countries, which makes it a lot harder to gain consensus there than with the Americans. Japan, obviously, is also an important player, but essentially those two are the biggest entities.
On June 7th, 2018. See this statement in context.