From February to April, Germany prepared Barbarossa in secret, and apart from the above contacts, no operational or political discussions were concluded during this time. Instead they published disinformation, such as claims that the German troop buildup in the East was merely a ruse ahead of a planned invasion of Britain (such a plan had been considered under the codename Operation Sea Lion) or safe training locations from British bombers, to hide their real intentions. When Germany invaded Yugoslavia and Greece beginning on April 6, suspicion of German intentions increased in Finland, though uncertainty still prevailed as to whether Hitler really intended to attack the Soviet Union before the Battle of Britain was concluded.