Israeli Chief of Staff Herzi Halevi raised the possibility of taking "action" against Iran on Tuesday, even as Prime Minister Benjamin Netanyahu's national security advisor downplayed any immediate threat posed by a new underground nuclear facility being developed by Tehran. So far, efforts by world powers to negotiate new restrictions on uranium enrichment and other projects that could be used to manufacture bombs have failed, prompting Israel to threaten to resort to force if it believes diplomacy has reached an impasse. Halevi stated, "Iran has advanced in uranium enrichment more than ever before... There are negative developments on the horizon that may necessitate (military) action." He did not detail the nature of these developments, nor what action might be taken and by whom. Halevi mentioned at the Herzliya Conference, an international security forum, "We have capabilities, and others have capabilities too," clearly referring to the United States, Israel's ally.