Sanctions, e.g., virtual blockades, are a favorite weapon of those who abhor war, but it's important to note that though they may be bloodless, they still cause casualties. The sanctions imposed on Iraq by the UN (including the US and Russia) after Saddam Hussein invaded Kuwait were very tough and collapsed the Iraqi economy, though they did include exceptions for food and medicine. Cynthia has mentioned the estimate that they might have been partly responsible for the excess deaths of up to 500,000 Iraqi children. Ironically, they did succeed in eliminating Iraqi weapons of mass destruction, the other ostensible purpose (besides Kuwait), but George W. Bush insisted on invading anyway. Of course it's arguable who was really most responsible for those deaths, the sanctions or Saddam, but there seems little doubt but that they were devastating.
The trouble with sanctions is that their impact falls heavily on those least responsible for the misbehavior targeted. Cuba is another case in point. The many privations of the Cuban people under Castro are do not only to Castro's bad economics and other crimes, but also to the sanctions imposed by the US. You can be sure that they didn't cause Fidel or Raul to miss many meals, but the average Cuban fared far worse. How many excess deaths among children can be attributed to those sanctions, I wonder?
This paper claims that the answer is not so many, mainly because, unlike Saddam, Castro moved aggressively to protect the most vulnerable.
Those sanctions were imposed because of the local political clout of the Cuban refugees, many of whom enjoyed a luxurious life style under Batista and his predecessors. Obama was able to end many of those sanctions because younger Cubans have seen their futility and the damage they do to ordinary Cubans.