In the 2011 Thor movie, how did the Jotuns land up on Earth to begin their invasion?
Did they use magic, the magic of which Loki speaks at the end of the movie? If it is so, why did they not use it again to invade/infiltrate Asgard, and wait for someone like Loki to help them inside?
In all likelihood, as it is not addressed in the movie (although possibly it is in the comics), the Jotun's either had a bridge like the bifrost which was destroyed in the first war with the Asgardians (?). Alternatively, on could postulate their ability to move between worlds relied on the Casket of Ancient Winters:
This casket was removed by Odin after the first war, and without it the Frost Giants were bound to their frozen home world, as punishment for invading Midgard.
