Washington, Feb. 7 -- US President Donald Trump signed an executive order renewing a national emergency over Iran and outlining a mechanism to impose tariffs on countries that do business with Tehran, the White House said on Friday.

The order allows the United States to levy additional duties on imports from nations that directly or indirectly purchase goods or services from Iran in an effort to protect American national security, foreign policy and economic interests. It does not set specific tariff levels but authorises officials to determine and adjust them based on changing circumstances.

The President may modify the Order if circumstances change, in response to retaliation, or if Iran or an affected country takes significant steps to...