Israel’s blistering counterattack to Iranian rocket fire at its soldiers early Thursday shows the country is determined to dislodge Tehran’s forces in Syria from its border, despite the risk of a wider Middle East war.

In what the Israeli military called its largest-ever operation inside Syria, warplanes made dozens of strikes against key Iranian infrastructure, an overwhelming response after an Iranian unit in Syria fired about 20 short-range artillery rockets that Israel said were either shot down or fell short of a nearby…