Israel announced on Tuesday that it had shot down a Syrian warplane over the occupied Golan Heights. Israel’s Army Radio said the aircraft crashed in the Syrian-held side of the frontier. The condition of the pilot was unclear. The military said it monitored the advance of the Syrian Sukhoi fighter jet and shot it down with a pair of Patriot missiles after it entered Israeli airspace by about two kilometers. It is only the second such incident along the border in 30 years. The military said that there had been an increase in the internal fighting in Syria since the morning hours, including an increase in the activity of the Syrian regime air force. It added the Israeli military was on high alert and would continue to protect its territory. Earlier, Israel sounded air defense sirens near the Syrian frontier and witnesses said the Israeli military launched two interceptor missiles, followed by the sound of explosions. It was the second such incident in two days on the Golan Heights, opposite Syrian areas where Damascuss forces have been routing opposition factions. Israel said two incoming Syrian rockets prompted Mondays alert and the launch of two interceptor missiles, but that the rockets fell short. On Monday, Israel rebuffed a new offer by regime ally Russia to keep Iranian forces in Syria away from the Golan Heights ceasefire line, an Israeli official said. The latest disagreement arose in a meeting between Israeli Prime Minister Benjamin Netanyahu and a senior Russian delegation dispatched to Jerusalem as regime forces advanced on the Golan. In Mondays meeting with Russian Foreign Minister Sergei Lavrov, Netanyahu turned down a Russian offer to keep Iranian forces 100 kilometers (62 miles) from the border, according to an Israeli official, who spoke on condition of anonymity. The official said that Netanyahu told Lavrov: "We will not allow the Iranians to establish themselves even 100 kilometers from the border." Israel had previously rejected a Russian proposal that Iranian forces be kept 80 km from the frontier, according to Israeli officials. Netanyahu held talks with Russian President Vladimir Putinin Moscow on July 11 amid Israeli concern that Syrian regime head Bashar al-Assad might defy a 1974 demilitarization deal on the Golan or allow his Iranian and Lebanese “Hezbollah” allies to deploy there. Russia has said that it wants to see the separation of forces on the frontier preserved.