Heads of state in three countries have so far taken part in escalating Twitter trash-talk before the next Invictus Games takes place in Orlando, Florida from the 8-12 of May 2016. The earlier light-hearted joshing between the Obamas, the Queen and Prince Harry seemed over until Monday, when Canada's Prime Minister Justin Trudeau got in on the act.

The playful baiting started with a nine-second video on 29 May, sent out from the First Lady of the United States' official Twitter account - it showed Michelle and Barack Obama standing in front of three armed forces personnel, ready to show what the US is bringing to the games. "Hey, Prince Harry," says the First Lady, "remember when you told us to bring it at the Invictus games?" "Careful what you wish for," adds the President, as two of the personnel either side make faces and the man in the centre mimes a mic drop while saying "boom".

The video was tweeted at the Kensington Palace account, who replied with their own video swiftly enough that they may just have known the other one was coming - under two hours. The reply video featured Prince Harry showing the Queen pictures from the first Invictus games when his phone rings with the FLOTUS message.

After watching the video, the Queen reacts with "Oh really, please," to which the Prince adds his own faux mic drop and "boom".

Not to be outdone (though seemingly uninvited), Canadian Prime Minister and all-round political heart-throb, Justin Trudeau waded into the social media mix. Flanked by members of Canada's Invictus Games team, Trudeau addresses the other leaders before flopping to the floor for a single push up. Luckily, the team has his back for their own mic drop and "boom" before Trudeau lets them know when and where to meet for the fight: "Orlando, Invictus Games, Canada's ready."

Justin Trudeau issues his own Invictus Games challenge to the Obamas and Prince HarryIBTimes UK

Along with the UK, US and Canada, 12 other countries are invited to take part in the games, though they have yet to issue their own smackdowns.

The Invictus Games were started by Prince Harry as a sporting event in which wounded armed service personnel could compete. The name Invictus comes from the Latin for "unconquered". The 2016 games, the second such event, takes place in Orlando, Florida; the 2017 games are to take place in Toronto, Canada.