Complex sentence: The Saab 36 was a planned attack aircraft that would be able to deliver nuclear weapons, and later on, submarines and aircraft, like the Lansen and ultimately Viggen, were considered as a means of delivery as well.
Split into simpler sentences: The Saab 36 was a planned attack aircraft that would be able to deliver nuclear weapons. Later on, submarines and aircrafts were configured as a means of delivery as well.