MUNICH — Israeli Prime Minister Benjamin Netanyahu warned Sunday his country will hit Iran directly if Tehran uses Syria to test Israel.

Describing Iran as the greatest threat to world security, Netanyahu brandished what he said was part of an Iranian drone fired from Syria last weekend.

“Last week its brazenness reached new heights” he said. “We will act without hesitation to defend ourselves. And we will act if necessary not just against Iran’s proxies but against Iran itself.”

In a major escalation that brought Iran and Israel to the brink of direct conflict, Israeli jets launched airstrikes in Syria last weekend after an Apache helicopter shot down the Iranian drone. Syrian antiaircraft missiles then shot down one of the F-16 fighter aircraft, the first time Israel had lost a jet in more than 30 years, and Israel then launched another larger attack on Iranian and Syrian military sites. The strikes took out half of Syrian President Bashar al-Assad’s air-defense capabilities, Israeli officials said.

An expanded version of this report appears on WSJ.com.

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