JERUSALEM — Israel braced for rockets and got a diplomatic bombshell instead.

The Obama administration’s surprise decision to delay a U.S. strike against Syria to allow for congressional debate left anxious Israelis relieved Sunday that any potential blow-back from Syria would be postponed for at least a week.

But there was hand-wringing inside government offices over how Obama’s hesitancy will be interpreted in the restive region and what it says about U.S. assurances to Israel that it will use military force to stop Iran from obtaining a nuclear bomb.

Many here viewed Obama’s last-minute equivocation as the latest evidence of a growing U.S. reluctance to engage aggressively in the Middle East, a worrisome prospect for a nation that relies heavily on its close American ties to intimidate enemies.

Even if the U.S. eventually punishes Syria for its alleged use of chemical weapons last month, Obama’s delay is expected to embolden those in Israel who argue for a unilateral military strike against Iran.

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And the upcoming congressional debate over Syria will complicate Israel’s effort to keep a low profile on the issue and avoid taking sides in what could become a partisan clash in Washington.

Not surprisingly, Obama’s announcement dominated the headlines and airwaves Sunday in Israel, where citizens had been rushing to get government-issued gas masks in anticipation that Syria or Iran would make good on their threat to bomb Israel in the event of a U.S. strike against Damascus.

Some praised Obama for putting the matter to a more rigorous debate. Many predicted the U.S. ultimately would still strike Syria and that the impact could be stronger with a united American front.

But in a region that tends to value military strength over democratic ideals, others lambasted Obama’s decision and said it would be seen as a sign of weakness.

“They are opening the champagne in Iran and probably switching to higher gear on their way to nuclear weapons,’’ said Housing Minister Uri Ariel, one of several Israeli lawmakers who ignored pleas from Prime Minister Benjamin Netanyahu to keep silent about the sensitive issue.

“If anyone really thinks this president will strike Iran based on evidence that Iranians have crossed the red line towards nuclear weapons, they must be hallucinating,’’ Ariel said.

Economy Minister Naftali Bennett, head of the nationalist Jewish Home party, said the delay exposed what he described as the worthlessness of international guarantees often offered by the U.S. and others to pressure Israel to restrain its military or make concessions to Palestinians.

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“The international stammering and hesitancy regarding Syria proves once again that Israel can rely on no one but itself,’’ Bennett wrote on his Facebook page. “From Munich 1938 to Damascus 2013, nothing has changed.” Bennett was referring to an international agreement signed in Munich in 1938 in which world powers acquiesced to Nazi Germany's annexation of part of Czechoslovakia.

Netanyahu, who did not comment directly Sunday on Washington's shift, sought to hit a chord of confidence despite the anxiety behind the scenes.

“Israel is calm and self-assured,’’ he said during a cabinet meeting Sunday.

But Israeli officials and analysts expressed concern that American deterrence in the region is waning.

“This isn’t about Syria, it’s about Iran,’’ said Jacob Dayan, the former Israeli consul general in Los Angeles. “If the U.S. is perceived as weak, that projects on Israel as well. We need the U.S. to be strong.”

As the only country in the Middle East believed to possess nuclear weapons, Israel has threatened to attack Iran’s purported nuclear program to prevent the Islamic regime from joining the nuclear club. Iran says its nuclear program is for peaceful purposes.