The president of the United States, everybody!
Apparently the victim was Dusko Markovic, the Prime Minister of Montenegro.
Luckily, Trump was very contrite about what he did.
Update, 12:30 PM: As one helpful commenter pointed out, it almost looks like, at the tail end of the video, Lithuanian president Dalia Grybauskaitė offers a handshake to President Trump, which he ignores. (He is famously not into shaking the hands of women!) Granted, it’s hard to tell if he actually saw her hand or not. What do you think?