What current events are discussed as the men await the ghost hamlet

Before the ghost of Hamlet's father appears, the three men, Marcellus, Bernando, and Horatio are talking about how the Norwegian prince Fortinbras is raising an army to attack Denmark and retake the land that Hamlet's father had taken from his father when he conquered them. Now that Hamlet Sr. is dead, there is no reason for him to withhold from attacking Denmark and taking what is his by right.