Reuters(Reuters) - A private door opens from Israeli Prime Minister Benjamin Netanyahu's office in central Jerusalem directly into a long, modestly furnished, half-paneled room decorated with modern paintings by Israeli artists and a copy of Israel's 1948 declaration of independence. It contains little more than a long wooden table, brown leather chairs and a single old-fashioned white projector screen.
This inner sanctum at the end of a corridor between Netanyahu's private room and the office of his top military adviser, is where one of the decade's most momentous military decisions could soon be taken: to launch an Israeli attack on Iran's nuclear program.
Time for that decision is fast running out and the mood in Jerusalem is hardening.
Iran continues to enrich uranium in defiance of international pressure, saying it needs the fuel for its civilian nuclear program. The West is convinced that Tehran's real objective is to build an atomic bomb - something which the Jewish state will never accept because its leaders consider a nuclear armed-Iran a threat to its very existence.
Adding to the international pressure, U.S. ambassador to Israel Daniel Shapiro said this week American military plans to strike Iran were "ready" and the option was "fully available".
The central role Iran plays in Netanyahu's deliberations is reflected in the huge map of the Middle East hanging by the door of his office. Israel lies on one edge, with Iran taking pride of place in the centre.
Experts say that within a few months, much of Iran's nuclear program will have been moved deep underground beneath the Fordow mountain, making a successful military strike much more difficult.
As the deadline for a decision draws nearer, the public pronouncements of Israel's top officials and military have changed. After hawkish warnings about a possible strike earlier this year, their language of late has been more guarded and clues to their intentions more difficult to discern.
"The top of the government has gone into lockdown," one official said. "Nobody is saying anything publicly. That in itself tells you a lot about where things stand."
Last week Netanyahu pulled off a spectacular political surprise, creating a coalition of national unity and delaying elections which everyone believed were inevitable. The maneuver also led to speculation that the Israeli leader wanted a broad, strong government to lead a military campaign.
The inclusion of the Iranian-born former Israeli chief of staff and veteran soldier, Gen. Shaul Mofaz, in the coalition, fuelled that speculation - even though both Mofaz and Netanyahu deny that Iran was mentioned in the coalition negotiations.
"I think they have made a decision to attack," said one senior Israeli figure with close ties to the leadership. "It is going to happen. The window of opportunity is before the U.S. presidential election in November. This way they will bounce the Americans into supporting them."
Those close to Netanyahu are more cautious, saying no assumptions should be made about an attack on Iran - an attack with such potentially devastating consequences across the volatile Middle East that Palestinian President Mahmoud Abbas even went so far as to predict in an interview with Reuters last week that it would be "the end of the world".
Israelis particularly fear retaliation from Iran's proxy militias - the Hezbollah guerrillas in southern Lebanon and the Hamas fighters in the Gaza Strip. Both are believed to possess large arsenals of rockets which could hit major Israeli towns and cities.
Hezbollah's deputy leader Sheikh Naim Qassem told Reuters in February that an Israeli attack on Iran would set the whole Middle East ablaze "with no limit to the fires". "Gone are the days when Israel decides to strike, and the people are silent," he said.
The Israeli Prime Minister and his key allies repeat for public consumption the mantra that economic sanctions against Iran must be given time to work and that now is not the time to speak about military options.
Top officials explain the new coalition on purely domestic grounds, saying it was needed to tackle the thorny and divisive issue of pressing Orthodox Jews into military service - in other words, that its formation has much more to do with the agenda inside Israel than abroad.
BURIED NUCLEAR STATES
Diplomats are divided. "I think the Iran thing is a red herring," said one senior Western envoy. "This is 98 percent about domestic politics". Others are less convinced.
Mofaz himself refuses to speak about military action against Iran, even in the theoretical.
A military veteran with almost 40 years' operational experience, whose office in the Israeli parliament displays a poster of Israeli warplanes flying low over the Auschwitz concentration camp, he scoffs at the idea that his Iranian descent gives him special influence on an Iran attack decision. He derides the idea any serious official in the know would talk to visiting journalists about such a sensitive military subject.
But behind the carefully evasive language of top officials, basic facts are clear. Time is running out. Iran's nuclear program - regarded by Netanyahu as an existential threat to the state of Israel - will soon be buried deep enough underground to render an Israeli attack impossible. The Jewish state's options are narrowing.
"I think they've gone into lockdown mode now," the senior Western diplomat said. "Whatever happens next, whatever they decide, we will not find out until it happens."
There are indeed those who see in Israeli posturing over Iran only bluff intended to press world powers into harsher sanctions and avoid war. Some military experts openly doubt how much damage Israel could inflict. The risk of a fiasco is big.
Perhaps the strongest clue as to Israel's real intentions is to be found in Netanyahu's private office, behind his desk. Officials say the Israeli premier was strongly influenced by his father, who died last month at the age of 102.
Benzion Netanyahu was a distinguished scholar of Jewish history and his strong sense of the past lives on in Benjamin, who laments to visitors that "most people's sense of history goes back to breakfast time".
On a shelf behind Netanyahu's desk, along with pictures of his family, is a photograph of Winston Churchill. Netanyahu admires the British wartime premier because he saw the true dangers posed by Nazi Germany to the world at a time when many other politicians argued for appeasing Hitler.
The parallels with modern-day Iran are obvious and Netanyahu is explicit about the dangers he believes are posed by militant Islam: as he puts it, its convulsive power, its cult of death and its ideological zeal.
But Churchill, although eloquent on the dangers posed by the rise of Nazi Germany during the 1930s, ultimately failed to prevent Hitler's ascent to power, the world war he unleashed or the Holocaust in which six million Jews were murdered.
Netanyahu, those who know him say, is determined to avoid going down in history as the man who shirked his opportunity to stop Iran going nuclear. (Additional reporting by Samia Nakhoul and Crispian Balmer; editing by Ralph Boulton)