Royals and Obamas Take to Social Media.
ALLEN: The U.S. first family and the British royals are publicly feuding. But it's all for a good cause. Barack Obama and Michelle Obama tweeted a challenge to Prince Harry over the upcoming Invictus Games, a competition for injured veterans. The prince responded and recruited Her Majesty for some help. Here is Phil Black with the story.</s>PHIL BLACK, CNN CORRESPONDENT (voice-over): This is a celebrity Twitter war like no other, the Obamas versus the royals, the White House versus Kensington Palace. Michelle and Barack Obama attacked first, posting on a video on Twitter Friday. And Prince Harry returned fire with a video of his own, featuring what has to be his most powerful weapon: his grandmother.</s>HENRY, PRINCE OF WALES: A message? Oh, from Michelle. How very amusing. Let us watch it together?</s>ELIZABETH II, QUEEN OF ENGLAND: Yes. So look.</s>MICHELLE OBAMA, U.S. FIRST LADY: Remember when you told us to bring it at the Invictus Games?</s>BARACK OBAMA, PRESIDENT OF THE UNITED STATES: Careful what you wish for.</s>UNIDENTIFIED MALE: Boom.</s>QUEEN ELIZABETH: Really, please.</s>PRINCE HARRY: Boom.</s>BLACK (voice-over): "Boom, really, please," wouldn't normally be considered a winning verbal smackdown. But it carries a little more power when it comes from the queen. The Obamas and the royals spent quite a bit of time together in London recently and have clearly developed a rapport. This is a good-natured attempt to develop a bit of friendly rivalry ahead of the upcoming Invictus Games, a sporting event for injured military veterans. It's a cause that Prince Harry is heavily involved in -- Phil Black, CNN, London.</s>ALLEN: Great story there to end on, thanks for watching, I'm Natalie Allen. "WINNING POST" is coming up in a few moments, right after our headlines.