The move comes as people in Iran mourn the killing of Iranian General Qasem Soleimani by the US in Iraq. He and other Iran-backed militia figures died in a drone strike ordered by Donald Trump last week. The head of Iran's military abroad, known as the Quds Force, General Soleimani was seen as one of the most powerful figures in the Islamic republic. He was also seen as the mastermind behind much of the country's activities across in the Middle East.
Mr Trump says the general was responsible for the deaths of millions of people. US Secretary of State Mike Pompeo defended the move.