and i think he was very keen to underline that in his news conference that i attended a little while ago. but asjoe biden goes back to america now on air force one, he has said, "we will respond if russia doesn't do what we want on cyber, on human rights and the rest of it," but respond how? that's the bit of it that is unclear, and i'm sure vladimir putin returning to moscow will be thinking, "well, he said these things, but what's he going to do about it?" vladimir putin has seen down western leaders before. maybe he will think that joe biden is a different sort of american president, but i think that vladimir putin is going to test it and joe biden will eventually have to decide how he is going to respond. i'm joined now by professor angela stent, an expert in russia—us relations and a former national intelligence officer for russia at the national intelligence council.