Sanctions against Iran have been in place in one form or another for decades and for multiple reasons. The fact that our "allies" choose to support a state sponsor of terrorism and a wannabe nuke power run by nutters is more a problem for them than us. If Iran goes rogue with nukes it will be the Europeans who get the worst of the result.
To look at Obamas Iran policies without looking at his middle east policies together, is a mistake. He failed to support the Iranians who might have risen up to change their government, he supported the Muslim Brotherhood in Egypt, he took out admittedly despotic leaders who at least were keeping Islamists under control. A part of that last was to facilitate the murder of Qaddafi and hand Lybia to the radicals. Doing that only showed future governments in the Middle East that making a deal with us was risky.
He ran guns to the Syrian rebels who were ISIS, and he abandoned the one good place for us to be, by leaving Iraq and turning much of that over the ISIS and Iran.
There is not one thing he did with these countries that ended up being a + for the US or for the world.
Irans assets had been frozen and confiscated for a number of reasons over the years. They were not only frozen by the US, but by the UN. Obama made a deal that could not be verified or enforced. He lied about when he started working toward the deal and with whom. Kerry was involved in making the contacts much earlier than we knew and with hardliners. Obama collected and sent cash to Iran in a way that was against the US laws which is why he sent foreign money, and it appeared to be ransome payment for hostages. Additionally, they calculated the interest on 400 million in the most favorable way to Iran. Oh yeah, and then he tried to give Iran access to US banks so they could convert the money, but the banks refused.
What has Iran been doing with the billions in cash? Why was Obama on the side of radicals every time?