President Barack Obama's executive order is designed to make it harder for Iran to evade existing sanctions. Tehran has been attempting to diversify the way it gets paid for oil sales, including by using gold and
barter
. Mr Obama's executive order also comes just as Congress prepares to vote this week on new legislation imposing even stricter sanctions on Iran. The bill will target any person or company which works with Iran's petroleum or natural gas sector. The move by the president seems to be an effort by the White House to show it's been just as tough on Iran as Congress.
The United Nations says that up to 18,000 people in the northern Syrian city of Aleppo have taken refuge in schools, mosques and other public buildings as fighting between government forces and rebels continues. Melissa Fleming from the UN refugee agency said some 7,000 people were sleeping in university dormitories as escape from besieged areas of the city has become too dangerous.
"We are witnessing that thousands of frightened residents are seeking shelter in schools, mosques, public buildings. These are the people who haven't fled the city. They haven't had the means or feared that it's too dangerous to make that journey. We are getting indications that the journey is rocked with armed gangs,
roadblocks
blocking the way.
World News from the BBC
The son of the late Libyan leader Muammar Gaddafi, Saif al-Islam, has said he wants to be