You have to ask Obama whats the use of "10% sanctions with waivers" ? Iran is mostly self-sufficient in food items, imported items like cars, gadgets etc are affected. Also has over $100 billion in cash reserves in tax-havens & gold bullion, which is enough for few years. A total naval & land blockade may have been more effective, but not such eye-wash sanctions. And since many countries like India, Turkey are co-operating with Iran in thwarting the sanctions, they are clearly not effective.
Australian hostage released by Al-Qaida in Burkina Faso; husband still held captive (AP)
from the article: Israel, U.S. mulling further sanctions on Iran