This cartoon by Chappatte from the International New York Times illustrates an Engish idiom. If someone plays hardball, they act aggressively and ruthlessly in order to get what they want. • He's a nice guy, but he can play hardball when he needs to.
In the cartoon Barack Obama is ready to play basketball (his preferred sport), but the other world leaders (Vladimir Putin, Chinese President Xi Jinping and Iranian President Hassan Rouhani) are equipped for a game of hardball (i.e., baseball). Putin has a baseball bat but he's holding it in a very threatening way, and Jinping's baseball gloves look more like boxing gloves. The message seems to be that Obama is not playing the same game as his counterparts, and needs to be tougher if he wants to achieve results in the various crises he's trying to deal with.