Lebanon's pro-western prime minister, Saad Hariri, is in Tehran to solicit vital Iranian support in keeping his country stable as tensions soar over a United Nations-backed probe into the assassination of his father.
Analysts in Tehran said his three-day visit is an unlikely vindication for Iran because it acknowledges that the Islamic republic has an important role to play in the region despite determined US efforts to contain its influence.
"From the political perspective, the visit can be very fruitful because with Iran and Lebanon entering a new phase of relations… [it] may pave the ground for Iran to play a direct role in solving Lebanon's problems," a hardline Iranian news and analysis website, Zaman, trumpeted yesterday.
There is widespread speculation that the international tribunal in coming weeks will implicate members of Hizbollah, the militant, Iranian-backed Lebanese Shiite movement, in the 2005 death of Rafik Hariri, Lebanon's former prime minister. Any such indictments, it is feared, could trigger clashes between Lebanon's Shiite and Sunni communities.
His son, the current Lebanese premier, is expected to seek Iran's endorsement of concerted diplomatic efforts by Saudi Arabia and Syria to help keep the peace in Lebanon if Hizbollah is implicated.
Regional powers fear that renewed violence in Lebanon could have an effect well beyond the borders of the small Levantine country - a point Mr Hariri stressed on the eve of his departure for Tehran on Friday.
"Impairing the stability of any country of the region is a threat to the interests of the Arabs and Iran at the same time," he said in a statement released by his office. "Therefore I consider that Iran is concerned by all efforts to provide elements of stability in all countries of the region, including Lebanon."
It is Mr Hariri's first visit as prime minister to Tehran. He is due today to meet President Mahmoud Ahmadinejad and the country's supreme leader, Ayatollah Ali Khamenei, Iranian state-run media reported.
Mr Hariri was quoted by Iran's official IRNA news agency on Friday saying: "The Islamic republic of Iran has a natural role in the region, especially in resolving crisis and strengthening stability in Lebanon."
Iranian state media yesterday also cited the Lebanese prime minister insisting that co-operation between Iran and Arab governments was essential to counter the threat from Israel, which is the "main threat" to the region.
Scott Lucas, an expert on Iran and US foreign policy at Birmingham University in England, said that Washington will tolerate Mr Hariri's Tehran visit "as long as he keeps the focus on Lebanon's stability".
But the US will be upset if the Lebanese prime minister criticises American-led sanctions on Iran over its nuclear programme, Mr Lucas added in a telephone interview.
Mr Hariri's trip, the result of an invitation from Iran, comes a little more than a month after Mr Ahmadinejad made a high-profile trip to Lebanon, where he was given a hero's welcome by Hizbollah, which is backed by Iran and Syria. But the Iranian president also had conciliatory words in Beirut about Lebanon's stability.
Hizbollah has denied any involvement in killing Rafik Hariri, who died in a 2005 truck-bombing along with 21 others. The movement's leader, Sheikh Hassan Nasrallah, has warned of dire consequences if the court indicts any Hizbollah members and has branded the tribunal an "Israeli project".
Tensions over the tribunal have already paralysed Mr Hariri's unity government, which includes Hizbollah ministers.
The Lebanese prime minister is committed to the UN-backed investigation, insisting he is "seeking justice" for Lebanon and not merely trying to find the truth about who killed his father.
But in recent months Mr Hariri recanted his original, strident allegation that Syria was behind his father's death, apparently accepting that no Lebanese leader can survive without good ties to neighbouring Damascus.
Iran shares Hizbollah's opposition to the tribunal but is said to be keen to help defuse the situation. The Iranian ambassador in Beirut, Ghadanfar Roknabadi, has been co-ordinating with his Saudi and Syrian counterparts. He described Mr Hariri's visit to Iran as "important" and "historic", insisting it would have positive results on Lebanon in coming weeks.
A Lebanese parliamentarian close to Mr Hariri, Okab Sakr, said the framework of a Saudi-Syrian initiative, that would ensure both "justice and stability", was in place but had yet to be finalised.
Iran, he told Reuters, was satisfied with the tentative deal. "If Iran objects, then it will stop, but actually there is an Iranian content."
Some analysts in Tehran and Beirut, who declined to be identified because of the sensitivity of the subject, suggested the deal will centre on Mr Hariri publicly accepting that if any Hizbollah members are indicted he will absolve the movement's leadership of responsibility.
There has been intense regional diplomacy to ward off sectarian strife in Lebanon. A joint visit to Beirut in July by the leaders of Syria and Saudi Arabia, who exercise great influence respectively among Lebanon's Shiites and Sunnis, has helped contain the situation.
And the Turkish prime minister, Recep Tayyip Erdogan, whose country enjoys good relations with Syria and Iran and has UN peacekeepers in southern Lebanon, visited Beirut last week where he pledged support for Lebanon's stability and unity. He underlined the importance of avoiding a civil conflict that could spread through the region.
Ankara has also helped foster rapprochement between Damascus and Riyadh, whose relations were strained during Israel's 2006 stalemated onslaught against Hizbollah in 2006.
Lebanese officials said that they were optimistic that the Saudi-Syrian initiative would find the solution to the Lebanese crisis but it was on pause until Saudi King Abdullah returns from medical treatment in the US.
Iran Daily, a government-run newspaper in Tehran, insisted that Mr Hariri's visit should not be reduced to the question of the UN tribunal, which is "an internal Lebanese affair".
It said in a commentary: "Hariri's visit can also be evaluated as a positive change in Tehan-Riyadh relations."