The combination of Iran’s progress toward the bomb, the failure of the US to “set red lines” for Iran, and the increasingly critical comments by the top US soldier about a possible Israeli strike on Iran, have left Israel with “a sharpened sense that it has no one to rely upon but itself,” a senior Israeli official said.

The anonymous official was quoted on Israel’s Channel 2 news on Saturday night. His comments came amid news that the US has significantly scaled back a major joint US-Israel missile defense drill next month.

The White House at the weekend reiterated its commitment to Israel’s security, but this drew a withering response from the Israeli source: “It’s hard to explain the gulf between the White House’s comments about the commitment to Israel’s security and the comments made by the US chief of staff,” the official said. “What matters are not words but deeds.”

Israel had already responded bitterly on Friday to comments by the chairman of the US Joint Chiefs of Staff, Gen. Martin Dempsey, who said on Thursday that he did not want “to be complicit” if Israel were to strike at Iran’s nuclear facilities.

A source in Jerusalem Friday called Dempsey’s comments “strange” and said they characterized the failure of the United States to take a determined position against Iran’s nuclear drive.

“It is strange that next to the oaths and blood libels of [Iran’s supreme leader Ayatollah Ali] Khamenei, the production in Iran [a reference to this week’s Non-Aligned Movement summit], and the [latest] IAEA report — which states that Iran is speeding up uranium enrichment under its nose — the American chief of staff decides to talk about [an Israeli strike] rather than giving a determined message to the Iranians,” the source said.

Speaking to journalists in London, Dempsey on Thursday made by far the clearest public comments from a senior American official distancing the US from any Israeli strike on Iran. He said an Israeli attack on Iran’s nuclear facilities, which is reportedly being seriously contemplated by Prime Minister Benjamin Netanyahu, would “clearly delay but probably not destroy Iran’s nuclear program.” Then he added: “I don’t want to be complicit if they [Israel] choose to do it.”

The “international coalition” applying pressure on Iran, warned Dempsey, “could be undone if [Iran] was attacked prematurely”. Sanctions against Iran were having an effect, and they should be given a reasonable chance to succeed, he added.

Israeli commentators made much Friday of Dempsey’s use of the word “complicit.” The US army chief could have said he did not want to be Israel’s “partner” or its “ally” in an attack on Iran, noted analyst Oren Nahari on Channel 1 state TV, but instead Dempsey employed a term with criminal connotations.

On the same channel, analyst Ari Shavit said that the events of the past week — including the publication of the IAEA report showing Iran expanding its nuclear enrichment program, and Iran’s hosting of the Non-Aligned Movement at which it declared it would continue its nuclear drive — showed that both diplomacy and sanctions have failed, and yet the US was doing nothing to ratchet up pressure on Iran.

Two weeks ago, Shavit noted, Israel’s President Shimon Peres publicly placed his faith in President Obama to thwart Iran’s drive to the bomb. America’s current policy, emblemized by Dempsey’s comments, said Shavit, “constitutes a resounding slap in the office for Peres and those other Israeli moderates who want to place their faith in the US.”

Given the US’s publicly stressed disinclination to act, “Israel is being pushed into a corner, in a way that is really dangerous,” said Shavit. “If all these moderate players, in the US and Europe, are so concerned about a dangerous Israeli action [against Iran], why haven’t they taken any meaningful action?” he asked.

Why, for instance, Shavit went on, did the US not condemn the Non-Aligned Movement gathering in Tehran. And why, asked Shavit, didn’t Obama “respond in his own voice to the IAEA report, which essentially said, ‘Mr Obama, you have failed’?”

Regional analyst Oded Granot said on the same program that Iran “does not think Obama will act” by force to stop its nuclear program.

On Channel 2, diplomatic reporter Udi Segal said comments like Dempsey’s might be bolstering the sense in the Israeli leadership that “maybe there’s no-one else who’s going to help us.”