SYRIA’S civil war escalated over the weekend when Israel launched a “large-scale attack” in the country against what it describes as “Iranian targets”.

The conflict of almost seven years has already drawn in several other nations, including the US, Russia and Turkey.

Israel has now sent warplanes to attack sites in the war-torn country, further complicating an already complex picture.

Why did Israel bomb targets in Syria?

Israel said it intercepted an Iranian drone that entered its airspace from Syria on Saturday. An Israeli F-16 fighter retaliated by attacking targets in Syria, before it was shot down by Syrian anti-aircraft fire, injuring the two pilots. It was the first time in more than a decade an Israeli jet has been lost in combat, according to The Jerusalem Post.

Israeli Prime Minister Benjamin Netanyahu defended the attack, saying his country delivered “severe blows to the Iranian and Syrian forces.”

“We will continue to strike at every attempt to strike at us,” he told his Cabinet.

Why did the Syrian civil war start?

The powder keg was lit in March 2011, amid the Arab Spring uprisings against autocratic regimes. A group in Syria showing their support were arrested and tortured by the regime of Syrian President Bashar Assad, sparking huge protests.

Assad’s forces responded by killing dozens, igniting a full-blown civil war to overthrow the regime. The growing chaos attracted terrorists from across the region, including remnants of al-Qaeda in Iraq and an offshoot that became the Islamic State (IS).

By 2014, IS militants began seizing large swaths of Syrian territory, including Raqqa as its de facto capital and the oil region Deir ez-Zor, as well as territory in Iraq.

Who are the major players and why are they there?

One by one, foreign countries started getting involved.

l The United States wants to root out IS. In September 2014, US warplanes that had been bombing IS forces in Iraq started bombing targets in Syria. The US is also working in Syria with the Kurds, one of the strongest and most reliable partners in the fight against IS.

l Russia entered the war in September 2015, using airstrikes to shore up the struggling Assad regime after a string of losses that threatened his control. Russian President Vladimir Putin has used the Syrian conflict to assert himself on the world stage.

l Iran stepped in to provide much-needed ground troops for the Assad regime, funnelling money and fighters through the Lebanon-based Hezbollah militant group to establish a strong presence in the region.

l Syria’s northern neighbour of Turkey became involved after it absorbed many refugees from the civil war. Turkey also fears the conflict will embolden its large population of Kurds to demand independence.

Since January, Turkey’s military started extending its ground operations into eastern Syria, near where US-led coalition forces have been battling the remnants of IS.

l Israel fears Iran could use Syrian territory to stage attacks on its small country or transfer weapons to Hezbollah, Lebanon’s Iranian-backed militant group. Iran is Israel’s arch-enemy and has sworn to destroy Israel. Jerusalem for years has been trying to make sure Tehran does not acquire nuclear weapons.

l In the shadows, Saudi Arabia and other countries in the Middle East have secretly backed armed fighters to overthrow Assad’s regime.

Could the battle extend beyond Syria?

All those forces operating in such close proximity creates a constant risk of a mistake that could trigger conflict outside Syria. On Saturday, Kurdish forces shot down a Turkish attack helicopter, the first officially confirmed loss of a Turkish aircraft over Syria. In January, a Russian fighter flew within five feet of a US reconnaissance plane before crossing the aircraft’s flight path over the Black Sea, according to the Military Times.

The US, in pursuit of IS fighters, has mistakenly killed Syrian forces, and Russia has accidentally struck US-backed forces. All sides have warned that such accidents could lead to larger wars.

Who is claiming the upper hand?

Russian airstrikes have helped Assad reclaim more control over his country. Assad’s forces have retaken the cities of Raqqa and Aleppo from IS troops, although small pockets of fighters still hold out in parts of the country. The Pentagon has said IS fighters have been cleared from more than 98 per cent of the territory they held at their peak in 2014 and 2015. Secretary of State Rex Tillerson said the US is committed to keeping a military presence in Syria to make sure IS does not regain a foothold.

What’s the situation on the ground?

The war has killed nearly half a million people and forced five million to flee, the majority to neighbouring Lebanon and Jordan. More than one million refugees landed in Europe, contributing to biggest migration crisis since the Second World War. According to the UN, nearly three million Syrian children have lived their entire lives gripped by civil war.

The civil war has destroyed historic cities such as Palmyra, which IS blew up in 2015. Russia is still bombing areas around Damascus not controlled by the regime, which activists say is causing scores of civilian deaths and many people are trapped without adequate food or medical care.

The U.S. has accused the Syrian government of using chlorine gas or other chemical weapons on civilians in rebel enclaves.