Transcript for President-Elect Donald Trump Returns to New York After His Holiday in Florida
Next president-elect trump is back in New York after his holiday in Florida, and back on a Twitter spree from his jab at Chicago's mayor to his gripe about a book cover photo. ABC's Mary Bruce has more from the white house. Reporter: After ringing in the new year at his annual bash in Florida, the president-elect is back home in trump tower -- and back on Twitter. Weighing in on the surging murder rate in Chicago, tweeting "If mayor can't do it he must ask for federal help!" A record-setting 762 murders last year. With 18 days until his inaugurat inauguration, trump is taking another victory lap, tweeting "Various immediate media outlets and pundits say that I thought I was going to lose the election. Wrong, it all came together in the last week." And he's complaining about a new book on the election, saying, they used the worst cover photo of me. But tonight, the big question -- what will trump reveal about the Russian hacking? I also know things that other people don't know, and so they cannot be sure of the situation. What do you know that we don't know? You'll find out Tuesday or Wednesday. Reporter: Trump is still pushing back against the conclusion of 17 U.S. Intelligence agencies that Russia was behind the hacking. I know a lot about hacking. And hacking is a very hard thing to prove. So it could be somebody else. Reporter: President Obama has just counterpunched with sanctions, but will trump keep them? His team says they are waiting on a full white house review. The idea that we're jumping to conclusions or actions you're going to take on a conclusion that are not final yet is unbelievably irresponsible. Reporter: Trump -- who despite his Twitter habit rarely uses a computer -- says there's only one way for sure to prevent cyber attacks. If you have something really important, write it out and have it delivered by courier, the old fashioned way, because I'll tell you what, no computer is safe. And Mary Bruce joins us now from the white house. President-elect trump had a very busy day on Twitter. Late night, he is weighing in with strong words for north Korea. Reporter: That's right. He is responding to the claim that they are preparing to test a long-ranged missile that could reach the U.S. He tweeted that it won't happen. We turn to a police arrest playing out on Facebook live.
This transcript has been automatically generated and may not be 100% accurate.