Korean media is abuzz over the question after the Microsoft founder was photographed Monday holding his hand in his pocket as he exchanged greetings with Park Geun-hye.
"Cultural difference, or an act of disrespect?" said the JoongAng Ilbo newspaper, according to The Telegraph.
Another newspaper, the Dong-A Ilbo, wrote "Disrespectful handshake? Casual handshake?" next to the photo.
Gates visited South Korea to promote his project TerraPower, which aims to develop a safe and next-generation nuclear reactor, and to give economic advice to Park Geun-hye, the Telegraph reports.