The warning signs are aligned, as the stars in the heavens portending a great event.
There are stirrings in Congress and intensified contacts with exile groups from the Middle Eastern country in question. Once more, President George W. Bush is warning that he has not ruled out the use of force to make sure that a regime linked to terrorism does not acquire weapons of mass destruction.
Most sensationally of all, a highly regarded magazine carries a detailed, only partially denied report that US special force units are already carrying out missions on the ground inside that country, pinpointing sites that could be hit by air-strikes or commando raids.
Back in mid 2002, all these things were happening as Washington prepared to demolish Saddam Hussein. This time however, the sights of the US are trained elsewhere.
Two years after invading Iraq, is America about to go to war with Iran?
The issue scarcely featured in the election campaign, but ever since Mr Bush defeated John Kerry last November, it has been clear that the Iran will be a crucial challenge of his second term. Even as US policymakers struggle to find an exit strategy from Iraq, they are obsessed by Iran.
Iran, not Iraq, is the issue likely to dominate Mr Bush's fence-mending visit to Brussels next month. Even more than Iraq, Iran has the potential to divide both the Bush administration and the Atlantic alliance.
"Only wimps stop at Baghdad," was the boast of the neo-conservatives in their hour of greatest glory, as US forces swept Saddam from power in a dazzling military campaign. Why be content with Baghdad, they argued. Why not carry the torch of freedom and democracy across the border to Tehran, that other founder member of Mr Bush's "axis of evil", toppling another dangerous and repressive regime.
But as even slightly chastened neo-cons now admit, Iran is quantitatively and qualitatively in a different league.
For one thing, unlike Iraq, it represents a genuine WMD threat. Saddam's chemical and biological weapons - not to mention his nuclear program - proved a figment of the Western intelligence services' imagination.
By contrast, inspectors from the IAEA, the nuclear watchdog agency of the United Nations, have been in Iran all along, and what they have encountered - a sophisticated, allegedly civilian, but largely impenetrable, nuclear program, as well as dissembling and downright lies from the Islamic regime - has been extremely worrying. Almost no-one doubts that Iran wants the bomb. Most experts believe it is roughly three years away from getting it.
Secondly, unlike Saddam's Iraq, the Iranian regime has proven ties with various Middle East terrorist groups, if not with al-Qa'ida itself, is explicitly committed to the destruction of Israel and has far more credible ambitions than Saddam ever had of becoming the dominant power in the Gulf, home of two thirds of proven oil reserves on the planet.
Thirdly, as a potential foe, Iran is on a different scale to Iraq. It is nearly three times as populous and its potential for mischief-making is unrivalled. Unlike Iraq, it could block the Straits of Hormuz, passage for 40 per cent of the world's traded oil. Iran is a Shia country, with close ties to, and potentially disruptive influence on, the Shia majority in Iraq.
For all these reasons, the US has held back. At present Washington is engaged in a "good cop, bad cop" routine with the help of the Europeans. Britain, France and Germany are leading a EU effort to strike a grand bargain with Iran, offering long-term economic and technological and diplomatic assistance to Iran in return for "objective guarantees" that Tehran has no military nuclear ambitions.
With studied reluctance, Washington has thus far gone along, maintaining its harsh rhetoric and strict trade sanctions, but allowing others to lead the way. "We've sanctioned ourselves out of influence with Iran," Mr Bush admitted at his pre-Christmas press conference. "In other words, we don't have much leverage with the Iranians right now."
But the bad cop is sending another message to Tehran: If negotiations fail force is very much an option. A nuclear-armed Iran is "unacceptable," Mr Bush has repeatedly said - and as the mullahs and the whole world knows, when the 43rd president says something, he means it.
At her confirmation hearings yesterday, Condoleezza Rice, the incoming Secretary of State, sounded a similar note: "We must remain united in insisting that Iran [and North Korea] abandon their nuclear weapons ambitions."
Meanwhile the familiar precursors of "regime change" are visible. The Pentagon is working with an Iranian exile group based in Iraq. In the US, exiles are forming organizations of their own, most notably the ADI or "Alliance for Democracy in Iran", which wants the Iranian people to hold a referendum to restore the monarchy, overthrown in 1979, under the former Shah's son, Reva Pahlavi (a resident of Washington's Virginia suburbs).
For Ahmad Chalabi, the Pentagon's pre-war poster boy for Iraqi "democracy", read Kamal Azari, president of the ADI. On Capitol Hill, conservative Republicans are pushing an Iran Freedom and Support Act, shades of the 1998 Iraq Liberation Act.
Then came this week's New Yorker article by Seymour Hersh, the investigative reporter who broke the Abu Ghraib prison scandal. Hersh claims that US commandos have already conducted missions inside Iran, dispatched by a Pentagon unabashed by the growing difficulties in Iraq and which, according to Hersh, has won its long battle with the CIA for control of US special force operations. The Pentagon issued a scornful dismissal of the story, but stopped well short of a full denial.
Just as before the Iraq war, the neo-conservatives, especially strongly represented in the Pentagon's civilian leadership, loudly demand action against Iran now. In their view, the EU initiative will fail - just as they were convinced the UN inspection would fail in pre-invasion Iraq. At that point however, the scenarios diverge.
The diplomatic uproar over an attack on Iran would eclipse the Iraq controversy. If the US went into Iran, it would do so virtually alone, with not even the semblance of the "Coalition of the Willing" that unseated Saddam. Even Britain would be missing. Instead Israel - the one country that could never go to war with Iraq - might be America's only ally, inflicting yet more damage, were that possible, to the standing of the US in the Islamic world.
The military attack itself would pose daunting problems. True, US forces are now based in Afghanistan and Iraq. But its military is overstretched and the 150,000 troops in Iraq (a third of them reservists and national guard) are tied down by the insurgency. If attacked, Iran would pull every lever to cause trouble in Iraq, and redouble its support for terrorist groups.
There is a second option, of smaller strikes from the air or commando raids aimed specifically at suspected nuclear sites and/or key military installations. These might be carried out with the help of Israel, which has warned that it cannot tolerate a nuclear-armed Iran. The implication is that Tel Aviv is ready to go ahead on its own, with (or perhaps even without) the tacit blessing of the US.
But even a smaller-scale attack is riddled with difficulties. Iran's nuclear sites are scattered and, by all accounts, well protected. This would be no repeat of 1981, when Israeli jets destroyed Saddam's reactor at Ozirak, setting back his nuclear ambitions by a decade. And would the humiliation of an attack, large-scale or small, really make the Iranian population rise up, as the neo-cons believe, to overthrow the detested mullahs? That calculation bids fair to join the long list of US misjudgments over Iran - from the coup that overthrew Mohammad Mossadegh, the nationalist prime minister, in 1953 and the failure to foresee the overthrow of the Shah in 1979.
The lessons of Iraq, including the debacle over non-existent WMD and the rush to embrace Chalabi, display the limits of US understanding of that country. Why should Iran be any different? If the post-war occupation and the absence of an "exit strategy" have been disasters in Iraq, they will be surely be double disasters in Iran.
Last autumn, at the height of the election campaign, the Atlantic Monthly organized a fascinating war game. At its center was a mock "principals" meeting on Iran to examine America's military options and and recommend the most suitable. Its conclusions were somber.
The magazine warned that next President - whom we now know to be Mr Bush - "must through bluff and patience, change the actions of a government whose motives he does not understand well, and over which his influence is limited."
Sam Gardiner, who for two decades has conducted such exercises at the National War College and who played the role of National Security Adviser, summed up its judgments in two blunt sentences. Mr President, "you have no military solution for the issues of Iran. You have to make diplomacy work".
The indications are that Mr Bush may grasped this reality; in other words a President who prides himself on telling it like it is, may for once be bluffing. Certainly his pre-inauguration deeds, as well as his words, tilt toward a strategy of negotiation.
It may be true that the most prominent foreign policymakers to depart the administration - Colin Powell and his deputy Richard Armitage - have been moderates, while the civilian architects of the Iraq mess, including the Deputy Defense Secretary, Paul Wolfowitz, and the Pentagon's Undersecretary for Policy, Douglas Feith, have kept their jobs.
But Condoleezza Rice is no neo-con and her deputy, Robert Zoellick - while a vigorous defender of US interests - comes from the old pragmatic and multilateralist Republican foreign policy mainstream. For the moment at least, John Bolton, the hawkish former Under Secretary of State whom many feared might be promoted to the No 2 job at State, is nowhere to be seen.
Moreover, the proclaimed policy of rebuilding fractured alliances with Europe and other allies would be a sham - and Mr Bush would know it to be - if he had already made up his mind to attack Iran.
But somehow America must deal with Iran. This administration's heart may say attack, but its head, it seems, says negotiate. This time the stick may have to be replaced by the carrot - an offer to Iran that combines economic aid from Europe with diplomatic recognition and a relaxing of sanctions by the US. Maybe a grand bargain can be struck. But, in the end, Washington may have no choice but to live with its nightmare: an Islamic theocracy which possesses nuclear weapons.
© 2005 Independent News & Media (UK) Ltd