black in moscow. phil, first off, talk about this newest development, this ultimatum. it certainly did ratchet things up. >> reporter: yeah, indeed that's right, ashleigh. what we understand from the ukrainian defense ministry, and this is the most significant of a number of ultimatums that russian military have given over the last 24 hours or so. really throughout this crisis. but we understand that the chief of the black sea fleet, the russian black sea fleet boarded a ukrainian vessel, and basically said you've got three choices. you can swear allegiance to the new crimean authorities, you can just simply surrender, or you can face attack. it at the moment, ukrainian defense officials haven't confirmed for us there is a time attached to this deadline. but they say that they have been receiving numerous deadlines in recent days and believe this is part of an ongoing psychological tactic by the russian authorities, by the russian forces, to try and drive them into surrendering and giving up. rjt phil, what about this new