Haaretz reports: Iran has not yet decided whether to make a nuclear bomb, according to the intelligence assessment Israeli officials will present later this week to Gen. Martin Dempsey, chairman of the U.S. Joint Chiefs of Staff.

Dempsey will be arriving on his first visit here since being appointed chairman of the Joint Chiefs of Staff in September. He will meet with various senior defense officials, including Defense Minister Ehud Barak and Israel Defense Forces Chief of Staff Benny Gantz.

The Israeli view is that while Iran continues to improve its nuclear capabilities, it has not yet decided whether to translate these capabilities into a nuclear weapon – or, more specifically, a nuclear warhead mounted atop a missile. Nor is it clear when Iran might make such a decision.

Israel also believes the Iranian regime now faces an unprecedented threat to its stability, which for the first time combines both external and internal pressure: from abroad, increasingly harsh sanctions and threats of military action, and at home, economic distress and worries about the results of the parliamentary election scheduled for March.

Israeli intelligence sees signs that the regime in Tehran is genuinely worried about the possibility of an opposition victory in March. Should that happen, the regime will have to choose between conceding the loss or falsifying results – as it apparently did in the 2009 presidential election – which could incite anti-regime protests thanks to the tailwind provided by the Arab Spring, which toppled the regimes in Egypt, Tunisia and Libya.

Moreover, the country’s economic woes are already hitting ordinary Iranians in their pockets. Tighter sanctions have caused the Iranian currency to depreciate by dozens of percent; the regime is having trouble amassing as much foreign currency as it needs; and now, it faces the prospect of new sanctions by the United States and the European Union against its central bank and its oil industry.

The regime is also being confronted by two distinct ideological challenges. On one hand, a growing camp that includes supporters of Iranian President Mahmoud Ahmadinejad is challenging the authority of the ruling clerics, and especially that of the supreme leader, Ayatollah Ali Khamenei. On the other, the Iranian model of a strict Islamic regime run by clerics is being called into question by Islamist ruling parties in Turkey, Tunisia and perhaps also Egypt, which either are or will soon be offering more democratic, modern and moderate models of Islamic governance.

Lastly, Tehran’s chief ally, Syrian President Bashar Assad, is in real danger of being toppled as well.

Altogether, therefore, “2011 was a very bad year for the regime in Tehran,” a senior defense official told Haaretz. Israeli analysts believe 2012 will promise more of the same: more pressure, including the tougher public line now being taken by U.S. President Barack Obama, and also more uncertainty and instability, in both the region as a whole and Iran in particular.

All this makes it increasingly hard to predict what Iran will do.