Israel shot down a Syrian fighter jet on Tuesday after it said the warplane crossed into the occupied Golan Heights, as Russian-backed Syrian forces regain control of territory from rebels along the volatile border.

Israel Defense Forces said it launched two surface-to-air Patriot missiles at a Syrian Sukhoi jet when it "entered about 1 mile [1.6 km] into Israeli airspace."

"The only thing we know about the aircraft is that it crashed, most likely in the southern part of the Syrian Golan Heights," Israeli military spokesman Jonathan Conricus told reporters.

He said that the plane was Syrian, not Russian, and had been monitored since it flew from the Syrian military airbase T4 in central Syria.

The UK-based Syrian Observatory for Human Rights, a war monitoring group, said that one pilot had died and the fate of the other was uncertain.

Disputed location of targeted jet

In recent days the Russian-backed offensive has reached the UN ceasefire line separating Syria and the Israeli-occupied Golan Heights, where a pocket of territory is controlled by the "Islamic State."

Syria's military claimed the jet was shot down over its airspace and Israel was helping "terrorists."

"The Israeli enemy confirms its support for the armed terrorist groups and targets one of our warplanes, which was striking their groups in the area of Saida on the edge of the Yarmouk Valley in Syrian airspace," according to an unnamed Syrian military source cited by Syria's SANA news agency.

Parts of the Golan Heights were occupied by Israeli following the 1973 Arab-Israeli war. Syria still claims sovereignty over the territory annexed by Israel.

Israel is worried that Syria's military will enter a buffer zone — monitored by the UN Disengagement Observer Force (UNDOF) — that borders Syria and the Israeli-occupied Golan Heights established in 1974.

It is also concerned that Syrian President Bashar Assad might allow Iranian and Lebanese Hezbollah forces backing his regime to deploy near the Golan Heights, despite Russian assurances that they will be kept at a distance from the border.

Fighting between Syrian forces and rebels has come up to the UN monitored buffer zone along the Golan Heights.

Israel holds red lines

Israeli Prime Minister Benjamin Netanyahu described Tuesday's incident as a "gross violaton" of the 1974 demilitarization agreement along the border area.

"We will not accept any such penetration or spillover into our territory, neither on the ground nor in the air. We insist that the Syrians strictly abide by the Separation of Forces Agreement between us and them," Netanyahu said.

The incident was the second time in two days that Israel has deployed its air defense systems in the Syrian border area.

Israel's David's Sling missile-defense system — also known as Magic Wand — fired at two Syrian surface-to-surface missiles on Monday morning, according to Haaretz, which cited the Israeli military.

Syria had launched two Soviet-made SS-21 missiles during internal fighting, reported Russia's TASS news agency.

Read more: Iran denies attacking Israeli positions

Who's fighting in the Syria conflict? War with no end Syria has been engulfed in a devastating civil war since 2011 after Syrian President Bashar Assad lost control over large parts of the country to multiple revolutionary groups. The conflict has since drawn in foreign powers and brought misery and death to Syrians.

Who's fighting in the Syria conflict? The dictator Syria's army, officially known as the Syrian Arab Army (SAA), is loyal to Syrian President Bashar al-Assad and is fighting to restore the president's rule over the entire country. The SAA has been fighting alongside a number of pro-Assad militias such as the National Defense Force and has cooperated with military advisors from Russia and Iran, which back Assad.

Who's fighting in the Syria conflict? The northern watchman Turkey, which is also part of the US-led coalition against IS, has actively supported rebels opposed to Assad. It has a tense relationship with its American allies over US cooperation with Kurdish fighters, who Ankara says are linked to the Kurdistan Workers' Party (PKK) fighting in Turkey. Turkey has launched multiple military offensives targeting Kurdish militias.

Who's fighting in the Syria conflict? The eastern guardian The Kremlin has proven to be a powerful friend to Assad. Russian air power and ground troops officially joined the fight in September 2015 after years of supplying the Syrian army. Moscow has come under fire from the international community for the high number of civilian casualties during its airstrikes. However, Russia's intervention turned the tide in war in favor of Assad.

Who's fighting in the Syria conflict? The western allies A US-led coalition of more than 50 countries, including Germany, began targeting IS and other terrorist targets with airstrikes in late 2014. The anti-IS coalition has dealt major setbacks to the militant group. The US has more than a thousand special forces in the country backing the Syrian Democratic Forces.

Who's fighting in the Syria conflict? The rebels The Free Syrian Army grew out of protests against the Assad regime that eventually turned violent. Along with other non-jihadist rebel groups, it seeks the ouster of President Assad and democratic elections. After suffering a number of defeats, many of its members defected to hardline militant groups. It garnered some support from the US and Turkey, but its strength has been greatly diminished.

Who's fighting in the Syria conflict? The resistance Fighting between Syrian Kurds and Islamists has become its own conflict. The US-led coalition against the "Islamic State" has backed the Syrian Democratic Forces, an alliance of Kurdish and Arab militias. The Kurdish YPG militia is the main component of the SDF. The Kurds have had a tacit understanding with Assad.

Who's fighting in the Syria conflict? The new jihadists "Islamic State" (IS) took advantage of regional chaos to capture vast swathes of territory in Iraq and Syria in 2014. Seeking to establish its own "caliphate," IS has become infamous for its fundamentalist brand of Islam and its mass atrocities. IS is on the brink of defeat after the US and Russia led separate military campaigns against the militant group.

Who's fighting in the Syria conflict? The old jihadists IS is not the only terrorist group that has ravaged Syria. A number of jihadist militant groups are fighting in the conflict, warring against various rebel factions and the Assad regime. One of the main jihadist factions is Hay'at Tahrir al-Sham, which controls most of Idlib province and has ties with al-Qaeda.

Who's fighting in the Syria conflict? The Persian shadow Iran has supported Syria, its only Arab ally, for decades. Eager to maintain its ally, Tehran has provided Damascus with strategic assistance, military training and ground troops when the conflict emerged in 2011. The Iran-backed Lebanese Shiite militant group Hezbollah also supports the Assad regime, fighting alongside Iranian forces and paramilitary groups in the country. Author: Elizabeth Schumacher, Alexander Pearson



Israel is suspected of carrying out dozens of airstrikes in Syria against Iranian forces and Hezbollah, including the T4 base from where the shot-down Sukhoi jet had taken off.

Just two months ago, Israel launched a large-scale rocket attack on several Iranian infrastructure targets in Syria. The strike came after Israel accused Iranian-backed forces of firing at their frontline troops in the Golan Heights.

cw,kw, rt (AFP, DPA, Reuters)

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