With today’s update, goblins are no longer mindless killing machines. Their main goal is to find and steal your valuables. They will of course pick a fight if your gnomes get in the way. However, it will be possible for goblins to arrive and steal something without any combat. In addition to that, goblins are now sending goblin tunnelers along with their raids. If a raid goes unsuccessfully, the goblins will return and attempt to dig a tunnel into your base. You can find the full patch notes here.