Politics in the Middle East over the past year has felt like being in the world’s most dangerous casino; Hamas, Hezbollah and Israel have all taken turns to spin the roulette wheel of escalation.

On Tuesday evening, Iran made arguably the biggest gamble of all when it fired 200 or so ballistic missiles at cities across Israel – an attack that could mark the start of a regional war that would leave global security in the balance.

For the past fortnight, Iran has been in a bind. Hezbollah, its most formidable proxy, has been rendered largely impotent – so far at least – by a stunningly successful Israeli military and intelligence campaign in Lebanon.

Israel’s onslaught has therefore left the Islamic regime with a stark choice. By doing nothing, it risked losing its standing in the Middle East, alienating Shias who look to Tehran as their lodestar and jeopardising its ambitions to be the region’s chief rival to Israel.

But retaliation risked all-out war with a technologically superior foe in a war that could draw in the United States. Such an outcome, cooler heads in the Iranian government reckoned, could end up threatening the country’s nuclear programme and perhaps even toppling the regime itself.

Tehran’s response has so far given every indication that it is seeking a Goldilocks solution by striking Israel with sufficient force to assuage domestic and Lebanese Shia opinion but without doing so much damage as to provoke a massive Israeli counter-strike.

Yet there is every chance that Iran will have achieved the worst of both worlds: not doing enough to restore Shia confidence in its leadership, while giving Benjamin Netanyahu, Israeli’s prime minister, the casus belli Tehran has long believed he wanted.

For the moment, Iran’s missile attack will have gone some way to mollifying Shia opinion. Chants of “God is great” could be heard from rooftops in several districts in Tehran, while joyful Shias fired into the air in Beirut in celebration.

They had longed to see an Iranian display of “shock and awe” and for many this was surely just the opening salvo.

Coupled with the terror attack on Tel Aviv’s light rail, in which gunmen shot dead at least eight people, they will feel a measure of revenge has been taken for the killing of Hassan Nasrallah and the crippling of the movement he led.

Yet Israel is likely to be neither shocked nor awed. Its defences intercepted the vast majority of Iran’s missiles, some of which fell harmlessly into the sea. Only one fatality has so far been recorded, that of a Palestinian man in the West Bank.

The success of the past two weeks may well persuade Mr Netanyahu to respond far more fiercely than Tehran may have bargained for.

Under heavy international pressure, he tempered his response to a barrage of 300 missiles and drones Iran fired at Israel in April in response to an Israeli strike on its embassy in Damascus.

Israel’s response was symbolic, but powerfully so, launching a missile strike that destroyed air defence systems at an airbase close to the Natanz nuclear complex south of Tehran. The message was clear: Iran’s nuclear assets are not as immune to attack as the regime may believe.

There are reasons to think that Israel could move beyond symbolism this time.

Iran long viewed Hezbollah as its chief insurance policy against an Israeli attack on its nuclear programme. If Israel struck, Iran would retaliate through the proxy it had helped equip with an arsenal of 150,000 rockets, some of them guided missiles capable of striking any city in Israel.

That deterrence has been significantly degraded in recent days, which is one reason why Israel may calculate that now is the time to strike.

The other is that, perversely, Iran may feel that, given it is no longer able to rely on Hezbollah as a nuclear insurance policy, it has no choice but to race for the bomb.

Iran has steadily increased its uranium enrichment programme over the years and is now sitting close to breakout capacity. Ayatollah Ali Khamenei, Iran’s supreme leader, may calculate that the only way to deter Israel is to drop all pretence and build a nuclear weapon.

If Israel calculates that this is Iran’s most likely policy, it is unlikely that any Western pressure will hold it back from a response that would tip the Middle East into the all-out war that everyone has feared.