SEOUL (Reuters) -Foreign leaders expressed condolences over the deadly crowd surge in Seoul’s Itaewon district, with at least 20 foreign nationals from as many as a dozen countries among those killed in the crush in a popular nightspot. South Korea’s President Yoon Suk-yeol declared a period of national mourning on Sunday after the Halloween crush on Saturday night killed some 153 people. South Korea’s Ministry of Interior and Safety put the total at 20 foreign nationals killed. A ministry official told Reuters that among the dead were people from China, Iran, Russia, the United States, Uzbeki…