It's difficult to predict, but one thing that you might watch for is a pause in the kind of missile and nuclear tests that we've seen. That might suggest that the regime feels that it's prepared to sit down at the table, having done the necessary work to test its systems.
There's good and bad news there. The bad news is that potentially they're only ready to sit down and talk once they feel they've perfected their intercontinental ballistic missile systems. But I think a pause in those kinds of tests would be a big indicator.