Barring a last-minute hitch, Iranian President Mahmoud Ahmadinejad is scheduled to arrive in Baghdad on Friday for what is tipped by both sides as an "historic visit".
Ahmadinejad will be the first Iranian president to visit Iraq and only the second Iranian government head in 32 years to do so. (The first was Prime Minister Amir Abbas Hoveyda who visited Iraq in 1976.)
Under normal circumstances, an Iranian government leader's visit to Iraq would arouse no apprehensions.
After all the two neighbours are linked with the tightest of historic, religious and cultural ties. More than 90 per cent of Iraqis live within 60 miles of the Iranian frontier. Millions of Iraqis, especially Kurds and Arab Shiites, share blood ties with Iranian tribes and clans across a 1,000-mile-long frontier.
Shiism, the faith of some 60 per cent of Iraqis, is shared by 87 per cent of Iranians who regard several Iraqi cities as holy. Since the fall of Saddam Hussain in 2003 some six million Iranians have visited these cities, accounting for almost half of all visitors.
In the past five years Iran has emerged as the biggest foreign investor in Iraq, mostly through religious endowments and private groups providing venture capital.
The two neighbours share important water resources not to mention some of the world's richest oilfields situated astride their common border. Basra, Iraq's largest port and Khorrmashahr, Iran's largest until its destruction by Saddam in 1981, cannot operate without at least normal relations between the two neighbours.
Estimated at less than $1 billion a year before the fall of Saddam, trade between Iran and Iraq has risen tenfold, partly through smuggling networks with political connections on both sides of the border.
The fact that Arab countries have virtually boycotted new Iraq, has enabled Iran to project itself as the only Muslim power sympathetic to the sufferings of the Iraqis under Baathist tyranny.
Iran's connections with some of new Iraq's leaders precede the creation of the Khomeinist regime in Tehran. Iran started supporting Iraqi Kurds against successive regimes in Baghdad as early as 1958. The Al Dawa (The Call) party, of which Prime Minister Nouri Al Maliki is a member, was created with Iranian financial, political and religious support in the early 1960s. The main Iraqi Shiite political group, the recently re-named Supreme Assembly of Islam in Iraq, was founded in Iran with the Islamic Republic's support in 1981. However, these are not normal times. Post-Saddam Iraq still depends on the United States for protection against domestic and foreign enemies. As long as there was a danger that Iraq might fall to radical Arab Sunni groups inspired and led by Al Qaida, Tehran did not object to that dependence.
Now, however, the picture is somewhat different.
As the possibility of Al Qaida and its allies winning recedes, Iran begins to focus on another danger to itself: the prospect of a Shiite-dominated but pro-American Iraq that might offer Iranians a rival model of society.
This is why, the Islamic Republic is determined not to let the Americans and their Iraqi allies succeed beyond defeating Al Qaida and the Sunni insurgency.
Seen from Tehran, the United States' historic mission was to remove Saddam, a mortal enemy of the Khomeinist regime, from power in Iraq, only to pave the way for its domination by Iran. The new Iraqi leadership elites under Al Maliki, however, do not want their country to become a satellite of Iran, and are trying to negotiate a long-term arrangement to keep the US committed to Iraq until it can defend itself.
Ahmadinejad believes that the US lacks the staying power to consolidate its victory in Iraq. He is encouraged by Senator Barack Obama's promise to withdraw all US troops by the end of 2009. (Ahmadinejad's entourage believe that the Democrat front-runner will win the American presidency in November).
Ahmadinejad's message to Iraqis is simple: the Americans are leaving, wouldn't you like to join our side?
During his visit, Ahmadinejad is expected to offer a multi-billion dollar package of aid and investment. He will also offer Iranian military assistance, including troops, to replace "the fleeing Americans".
Tehran's promises come coupled with implicit threats to those who might not want to switch sides by abandoning the Americans.
Last week, Iraqi police uncovered an Iranian-sponsored plot to assassinate Mohammad Al Wanli, the Governor of Basra and his brother.
Apart from showing the flag and leaving his visiting card, Ahmadinejad will use the Iraq trip as a photo opportunity to boost his own position just days before the parliamentary elections scheduled for March 14.
Although he has no official list of candidates, Ahmadinejad is clearly identified with hardliners who hope to retain control of the Islamic Majlis (parliament) in support of his radical agenda.
He has asked to see Grand Ayatollah Ali Mohammad Sistani, the primus inter pares of the Shiite clergy and hopes to obtain TV footage of the occasion. That would help the Iranian visitor boost his religious credentials and weaken the position of the mullahs opposed to his radical policies.
The visit will enable Iraqis to have a close look at Ahmadinejad. He hopes they will find him a model to follow. Iraqi leaders hope he would appear more like a warning.
Amir Taheri is an Iranian author based in Europe.