has been cut off. they are feeling the squeeze, but they have made progress. martha: to that line of thinking, the united states just flew a b-1 supersonic bomber over north korea, a very aggressive exercise. obviously response to the icbm test race, and in response, we are seeing chinese drills in place where we haven t seen them in the yellow sea and east c. saying, this is a message from china to president trump not to provoke pyongyang any further. does that indicate that china is, perhaps, on the other side of the line, that if we were to do a preemptive strike that they might defend north korea? all of the calls that have happened between president xi and president trump have been strong, positive calls. he has asked president xi to cut off the oil, because the last time they did, north korea came to the table. they have come through and the sanctions, but they haven t gone that far. there is more they can do, we re