The response in Israeli defense circles to the news of John Bolton’s appointment as U.S. national security adviser was much more sober than that the cries of joy that erupted in Israeli political circles. The amount of influence a single senior official can wield in the current administration is still open to question. The unprecedented churn around U.S. President Donald Trump has in many cases prevented high-ranking figures from leaving their mark before being informed, by Twitter or by more traditional channels, that the president no longer requires their services.

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The work of the administration, in which many senior positions are still not filled, has so far been characterized by confusion, improvisation and lack of long-term planning. And yet, the entry of Bolton and Mike Pompeo (as secretary of state), replacing H.R. McMaster and Rex Tillerson, might signal a bigger change. Not only because they are considered hawks, but also because at least Bolton is perceived in Israel as a man of action, who is able to implement his ideas.

Bolton’s appointment suggests that Trump plans to withdraw from the Iranian nuclear deal on the next deadline, May 12. According to the intelligence assessment presented to political officials, Tehran faces more pressure than it has since the agreement was signed, in July 2015, for several reasons. While former U.S. President Barack Obama saw the deal as his greatest foreign-policy achievement, Trump has vowed to scrap it.

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In addition, Iran’s economy has not bounced back after the easing of sanctions as much as leaders had expected. At 78, Iran’s supreme religious leader Ayatollah Ali Khamenei is ailing, the conflict between Iranian President Hassan Rohani and the Iranian Revolutionary Guards (some of it around aid to Syria, Hezbollah and the Houthi rebels in Yemen) has not ebbed and the protests this year highlighted public frustration. Israel’s intelligence community sees this situation as a window of opportunity for extracting more concessions from Iran in renewed negotiations on the nuclear deal and in other areas — presumably through new threats of economic sanctions and perhaps even U.S. military force.

Israel hopes not only to fix the Vienna agreement, which makes it easier for Iran to resume its nuclear program after the deal expires and does not sufficiently monitor research and development. Israel also believes gains could be made in moving Iranian and pro-Iranian forces further from Israel’s border with Syria, restricting Iran’s missile program and reducing its military aid to Hezbollah.

As always, the Achilles heel of these expectations is in the Trump administration, whose hawkishness appeals to Israel. The president and his aides have proven difficulties with long-term planning and with implementation. Even assuming the hardening of the U.S. position vis-a-vis Iran is strategically advantageous to Israel (a controversial assumption), it’s still not clear that the administration can follow through, and do so without dragging the region into a military conflict.