JERUSALEM, March 11 (JTA) — The Israel Defense Force chief of staff, Lt. Gen. Amnon Shahak, left this week for visits to South Africa and Thailand with the goal of strengthening Israel’s military ties with the two states. Israel has been concerned by a South African proposal to sell tank firing systems to Syria. In another development, Turkey’s defense minister is due to visit Israel next month in what will be the first such trip by such a Turkish minister. During the past year, Israel and Turkey strengthened their military ties with a number of cooperation agreements — including plans for joint air maneuvers in Turkish air space — that have drawn sharp criticism from Arab states. Last month, the two countries launched a $632.5 million project in which Israel will upgrade 54 Turkish F-4 fighter jets.