Talking to Kim - what about?

Rex Tillerson is quite a tease. He has revealed that Washington is talking direct to Pyongyang. So who exactly is talking to whom? Surely not Kim himself? After all his vows to annihilate the US, how do you start the conversation? Perhaps it's one of his fawning generals, but he wouldn't be able to say anything without the authority of Kim. So, again, how does the conversation develop, unless Kim is in the same room?i That could make for a very tricky chat, with Kim mouthing from across the room about refusing to give up his nuclear bombs. Still, it's a breakthrough. It has to be good that Washington and Pyongyang are having a little talk, even if it's about the weather. So when did these chats begin? Surely not during the mad, crazy rhetorical sniping that has been going on between Trump and Kim Jong-un. That would be weird to say the least. This dialogue must have begun AFTER the threats of war, to try and calm things down. So I'm assuming there'll be no more "Rocket Man" stuff in Trump tweets. Who knows, perhaps Trump and Kim will get to like each other!! Despite what Tillerson revealed, I for one do not feel totally reassured because I'm still convinced that whatever words are passed down the telephone line, Kim wants to be a nuclear warlord, he wants parity with Trump. Only then will the little chats have any real meaning. But we shall see. Better talk talk than war war.