Mahmoud Ahmadinejad, the Iranian President, is to inflame tensions in the Middle East with a two-day trip to Lebanon during which he plans to make a provocative tour of the border with Israel.
Iranian officials have indicated that the hardline leader plans to throw a "symbolic" stone at an Israeli border point during his visit, which starts tomorrow.
While Mr Ahmadinejad will make the journey to the south with Lebanon's President Michel Sleiman, a Christian, most of the rest his efforts will be devoted to Hezbollah, Iran's principal ally in the divided country.
It is thought that he will share a stage with Hassan Nasrallah, the Shia Muslim group's leader, who spends most of his time in hiding from the threat of Israeli assassination.
Iran is accused of providing hundreds of millions of pounds of funding to Hezbollah, which has been proscribed as a terrorist organisation by both the UK and the US.
Israel lobbied Washington to use its clout to prevent the visit but, with Hizbollah a coalition partner in Beirut's government of national unity, the US pleas were rebuffed.
The two presidents also intend to sign a series of agreements on Iran providing military aid to Lebanon and exploring its territorial waters for offshore gas, sparking warnings that Lebanon must uphold sanctions that bar it from striking a weapons deal with Iran.
The US currently supplies Lebanon with all the weapons for its military but it is threatening to block further sales after a gun was used on an Israeli soldier, it is understood that Iran may try to bridge the gap.
Mr Ahmadinejad will make his stone-throwing gesture after a trip to Bint Jbeil, the village that bore the brunt of Israel's offensive against Lebanon in the 2006 war and has since been rebuild with Iranian money.
Officials in Tel Aviv are resigned to Mr Ahmadinejad, who has questioned the Holocaust and called for the state to be wiped out, posturing on their doorstep.
Yigal Palmor, a Foreign Ministry spokesman said: "He will arrive in Lebanon, and everyone understands the significance of this."
After its abortive diplomatic drive to prevent the visit, US State Department warned Mr Ahmadinejad that he was playing with fire.
"Throwing stones, whether they're literal or figurative, I would not consider constructive," PJ Crowley, the State Department spokesman said.
Yesterday British diplomats warned the Lebanese government that it must uphold UN resolutions that bar it from weapons deals with Iran.
Hezbollah strongholds have been bedecked with giant portraits of the Iranian leader. Tens of thousands of Hezbollah faithful will pack a football stadium in the south of the capital tonight to listen to Mr Ahmadinejad.
The emboldening effect on Hezbollah's followers will be greeted with trepidation by the rest of the Lebanese population at a time when the movement is preparing to defy international pressure to hand over suspects expected to be named by a special international tribunal for the murder of former Prime Minister Rafik Hariri in 2005. Hezbollah has threatened to bring down the government if the tribunal is not wound up.