DUBAI (Reuters) - Iran has blacklisted the U.S. ambassador in Yemen, the Iranian foreign ministry said on Wednesday, a day after Washington imposed terrorism-related sanctions on Tehran’s envoy to the Yemeni Houthis. Tehran’s move, which allows the seizure of assets within Iran of sanctioned individuals, is symbolic and unlikely to have any impact on the U.S. ambassador. “Highlighting his key role in Yemen’s humanitarian crisis, Iran puts Christopher Henzel’s name on its sanctions list,” the ministry said in a statement on its website. On Tuesday, the U.S. Treasury blacklisted Hasan Irlu, Iran’s ambassador to the Houthis, describing him as a pillar of Iranian efforts to project its power in Yemen, Syria and elsewhere. Yemen has been locked in conflict since 2014, when the Iran-aligned Houthis group seized Sanaa, the capital, and then much of the country’s north. Iran’s regional foe Saudi Arabia is leading a Sunni Arab coalition fighting the Houthis in the impoverished state on the tip of the Arabian peninsula. The conflict is widely seen as a proxy war between Saudi Arabia and Iran.