Well, maybe if the Pussy-grabber In Chief had attended security briefings or watched News that wasn't Fox, he would have know. It was announced in November and made the New York Times. My guess is that it was in a Security Briefing that he didn't attend (because he doesn't need to hear the same stuff all the time - he is Very Smart).
I don't mean this rudely, but as an observation.
President Trump is a bit like a two year old in that he seems to think if he didn't actually witness it, it didn't happen. Now in America, the media let's him get away with this all the time (tax returns, crowd size, nuclear option) but, in the international arena that shit don't fly. We aren't playing beak-a-boo here anymore. NATO, the EU, Crimea, the Iran Deal, Climate Change, the Australian Deal. All of these things pre-date your administration - and yet they are still going on. You can't renegotiate everything.