The Department of Homeland Security sought on Friday to clarify its announcement last week that immigrants seeking permanent residency would have to return to their home countries to await their green cards, claiming there was no major change in policy and that only some will have to go back. The clarification appeared to be a partial walk-back of an announcement in a U.S. Citizenship and Immigration Services news release last week. Despite a long-standing policy of allowing immigrants to remain in the country while they wait for their green cards, it said individuals would now have to go back while they wait except in “extraordinary” cases. But on Friday, the Homeland Security Department said it was not a blanket change and that it would be up to individual immigration officers to decide whether someone should be forced to go abroad to gain a green card. They said that officers have long had such discretion.…