Israel’s unprecedented strikes on 20 military targets inside Iran on Saturday show how vastly and rapidly long-standing deterrence calculus in the Middle East is shifting after more than a year of escalating conflict.

The Iran-Israel conflict was once largely limited to a shadow war. On the Israeli side, it was marked by assassinations, sabotage and computer virus attacks against Iranian nuclear scientists, and on the Iranian side, by the build-up of allied militias ready to target Israel.

Now Iran and Israel are openly striking each other’s territory with blows that until recently seemed unthinkable.

Earlier on Saturday, Israel disabled Iran’s four remaining Russian-made S-300 surface-to-air missile batteries and key radar arrays, apparently paving the way for possible future attacks. Last year, Israel inflicted great damage on Hamas and now went after Hezbollah.

“Iran’s deterrence is ruined,” says Ali Vaez, director of the Iran Project at the International Crisis Group in Washington.

Still, Tehran’s view is that Iran’s deterrence calculations against Israel are still largely valid, says Hasan Ahmadian of Tehran University, adding that some say Iran’s mistake was not responding more quickly to Israel in previous attacks.

“So I’m pretty sure Iran will do something directly against Israel,” he says.

Israel’s unprecedented strikes on 20 military targets in arch-enemy Iran on Saturday show how far and how quickly longstanding deterrence calculus in the Middle East has shifted after more than a year of conflict.

The Iran-Israel conflict was once largely limited to a shadow war. On the Israeli side, it was marked by assassinations, sabotage and computer virus attacks against Iranian nuclear scientists, and on the Iranian side, by the build-up of allied militias ready to target Israel, from Lebanon and Gaza to Yemen.

Now Iran and Israel are openly striking each other’s territory with blows that until recently seemed unthinkable.

Before dawn on Saturday, Israel struck Iran’s air defenses, apparently knocking out Iran’s four remaining Russian-made S-300 surface-to-air missile batteries and key radar arrays protecting key energy facilities, paving the way for possible future attacks.

Israel also targeted advanced industrial mixing machines used to blend solid fuel for Iran’s ballistic missile arsenal; these machines would be needed to replace the missiles fired at Israel.

Israeli Prime Minister Benjamin Netanyahu said Israel had “dealt a hard blow to Iran’s defense capabilities and its ability to produce missiles targeting us.” Iran’s supreme leader, Ayatollah Ali Khamenei, said the attacks “should neither be exaggerated nor underestimated” and did not mention retaliation, despite other officials saying so.