As I said, this is planned for US domestic politics;
Elections are nearing, campaigning runs already... Obama needs something to make him look like a national hero. What's better than saving two Americans from evil Iranians who American people hate (though most even don't know where this particular country is located) ?
This gives Obama also chance to appear as a negotiating president. He won't use brutal force, because he can't but also to prove his more discreet policy is the right choice. Watch. They won't be held 8 years in Iran.