Inside the bunker under Tel Aviv

A cavernous space has been carved out of the ground two floors below street level.

Overhead, it’s another scorching summer’s day in Tel Aviv, Israel’s biggest and busiest city.

But down here, under the neon lights, a massive, blast proof steel door swings open to reveal a hidden realm.

Locked away from today’s bright sunlight, it feels like a gloomy and surreal under world.

But soon enough, it might be all too real.

"This is one our newest bomb-shelters," Asaf Zamir, Deputy Mayor of the city tells me as he shows off, with no little pride, the facilities. "Here there’s space for 400 people."

There are, he tells me, 241 public shelters in the city. This, like another 110, are proof against chemical attack.

"There’s air conditioning, toilets and water. And two showers. I think the queues might be long," Zamir jokes.

But this is deadly serious.

In the event of war, Tel Aviv would be high on the list of targets of Israel’s enemies.

This is a country that is permanently on a war footing.

But this summer there is an added sense of urgency. And in many minds, a growing sense of inevitability about war with Iran.

An intense debate has played out, both on and off the record, in Israel’s news media.

Wade through the oceans of words written and spoken and a single, simple narrative emerges time and again.

Prime Minister Benjamin Netanyahu and Defence Minister Ehud Barak are all but convinced that the only way to stop Iran’s progress towards nuclear weapons is to launch air-strikes on their research centres.

Against them are ranged the top ranks of Israel’s defence and intelligence establishment. And their voices urge caution.

Inside the bunker

Among them, Major General Aharon Zeevi Farkash; until 2006, chief of military intelligence. Now in retirement, he remains it seems in touch with the top level debate raging behind closed doors.

He grants us a rare interview. He has chosen to speak out because he is concerned that Israel is about to make a costly mistake.

"I worry about the day after an Israeli strike," he tells me."Hezbollah has 60,000 rockets, Hamas 30 to 40,000 rockets. And I am afraid that this would be a wonderful reason for Bashar Al Assad to launch his missiles at us."

The general says Israelis would not fear the consequences of war if they were convinced that in suffering they would end the threat from Iran.

But he predicts that unilateral military action by Israel would simply unite the rival factions crowding round the rule of President Mahmoud Ahmadinejad.

"In any case, I believe it is impossible to destroy all the infrastructure and targets connected with the Iranian nuclear plan. It’s impossible. I’m not even sure we know everything that we need to know.

"Because of that it is my opinion to try not to do this alone."

Instead he thinks sanctions and diplomacy, backed by the threat of US-led military action, should be given longer to work.

"Finally I think western leaders realise a nuclear Iran is the number one challenge facing the world.

"Therefore with this coalition I can see results. I strongly believe we have the time, maybe eight or nine months."

The showers - queues could be quite long

Neither Netanyahu nor Barak share his confidence in sanctions, or his assessment of the available timescale.

Zeevi Farkash thinks they’ll want to make a decision on airstrikes, "in the next two months."

I ask him if political leaders can push through military action, even in defiance of the advice coming from the top brass.

"I have been in these intimate meetings making the tough decisions," he replies. "I have never seen that happen in the past so I hope it will not happen in the future.

"Back in the Tel Aviv bunker, deputy mayor Zamir tells me the city is as ready as it ever can be for war.

"All this talk (of war) in the papers has created a sense of panic among people." he says.

I ask him if he’s confident Tel Aviv will survive, whatever comes.

He pauses for several seconds.

"I’m optimistic," he replies.