Israel must be prepared for a long-term standoff and instability in Syria while deterring the "axis of evil" - Tehran, Damascus and Beirut - from winning the conflict, Defense Minister Moshe Ya'alon said Wednesday. "Instability in the Middle East is due in part because the Iranian regime is involved in every conflict taking place in the region," Ya'alon told Gen. Martin Dempsey, chairman of the US Joint Chiefs of Staff during his visit to Israel. The two military chiefs discussed the current issues in the Middle East at a meeting also attended by IDF Chief of Staff Benny Gantz. American media outlets quoted Dempsey this week as saying that Washington is getting a better picture of moderate Syrian rebel organizations it seeks to support against the regime of Bashar Assad.During the meeting, Dempsey reiterated US commitment to Israel and the "shared security interests" faced by both while Ya'alon expressed his interest in further strengthening Israeli-US relations. Ya'alon stated that change was the primary factor in the Middle East, and Dempsey's visit posed an opportunity to discuss the situation in the region and various courses of action. He added that while the US and Israel face many challenges ahead in the Middle East, "we share common interests and shared values."Dempsey met with Prime Minister Binyamin Netanyahu on Tuesday to hold key security talks on Iran, Syria and the Egyptian Sinai.The US military chief will next travel to Jordan, where the US has kept military forces, including an F-16 squadron, on standby for potential developments in neighboring Syria.Yaakov Lapin and Herb Keinon contributed to this report.