Measures hit banks, oil, trade

How the sanctions put pressure on Teheran:

Financial/banking: Sanctions administered by the Treasury Department in Washington sought to isolate Iran from both the US and international financial systems.

Oil exports: Before 2012, half of Iran's government revenues came from oil exports. The sanctions cut its oil exports by more than half.

Trade: The US has had an embargo in place since 1995 that prohibits most domestic companies from trading with or investing in Iran.

Asset freezes and travel bans: US allies have cooperated in freezing Iranian assets worth huge sums of money. Two years ago, Iran held an estimated $100 billion in various currencies in accounts outside the country, but Teheran could access only $20 billion.

Weapons development: The US Iran-Iraq Arms Nonproliferation Act of 1992 calls for the sanctioning of any person or entity that assists Teheran in weapons development or the acquisition of "chemical, biological, nuclear, or destabilizing numbers and types of advanced conventional weapons".

Sources: The Fiscal Times, Council on Foreign Relations