10, FEB, 2018 — In its most serious engagement in neighboring Syria since fighting there began in 2011, Israel shot down an infiltrating Iranian drone Saturday and struck Iranian targets deep in Syria before one of its own jets was downed.

The sudden escalation offers what could be a harbinger of what lies ahead as the Syrian fighting winds down and an emboldened Iran establishes a military presence that Israel vows it will never accept.

Israel has issued several stern warnings of late about the increased Iranian involvement along its border in Syria and Lebanon. The Israeli Cabinet just held a meeting near the Syrian border to highlight the new threats, which it attributes to Iran’s growing confidence given the success of the government of Bashar Assad in the Syrian civil war thanks to their support.

Israel called the drone infiltration a “severe and irregular violation of Israeli sovereignty” and warned that Iran would be held accountable for its meddling, raising the specter of a larger confrontation in an area that has remained largely stable since a monthlong war between Israel and Hezbollah in Lebanon in 2006.

“This is a serious Iranian attack on Israeli territory. Iran is dragging the region into an adventure in which it doesn’t know how it will end,” Israel’s chief military spokesman, Brig. Gen. Ronen Manelis, said in a special statement. “Whoever is responsible for this incident is the one who will pay the price.”

Israel would not confirm whether the aircraft was actually shot down by enemy fire, which would mark the first such instance for Israel since 1982 during the first Lebanon war.

Israel fears Iran could use Syrian territory to stage attacks or create a land corridor from Iran to Lebanon that could allow it to transfer weapons more easily to Hezbollah — Lebanon’s Iranian-backed political party and militant group sworn to Israel’s destruction. Though Israel has largely stayed out of the Syrian conflict, it has struck weapons convoys destined for Hezbollah — which is fighting alongside Syrian forces — almost 100 times since 2012.

In subsequent attacks, the Israeli military said it struck four additional Iranian positions and eight Syrian sites, causing significant damage. The Israeli jets again faced a heavy barrage of anti-aircraft missiles but returned home safely, as large explosions were reported in Syria and warning sirens blared in northern Israel.

Israel has shot down several drones that previously tried to infiltrate its territory from Syria. The capture of an Iranian drone and the targeting of Iranian sites in response, however, marked a dramatic escalation in the Israeli retaliation. The military confirmed that the initial target in Syria — the unmanned aircraft’s launch components — was successfully destroyed and released grainy footage of the strike. Israel also said it had recovered the remnants of the drone, which proved that it belonged to Iran.