|Al-Assad, right, and Ahmadinejad will meet to discuss "the exceptional ties" between the two countries [File: EPA]
Bashar al-Assad, the Syrian president, has arrived in Tehran on a trip aimed at reassuring Iranian leaders that the alliance between the two countries is solid despite Syria's improved relations with the US.
The official Syrian news agency said al-Assad will meet Mahmoud Ahmadinejad, the Iranian president, and other officials on Saturday to discuss "the exceptional ties" between the two countries and the latest international developments.
The visit comes less than a week after Hillary Clinton, the US secretary of state, met Walid al-Moualem, the Syrian foreign minister, in New York. Al-Assad had earlier met George Mitchell, President Barack Obama's Middle East envoy, who is now trying to save Palestinian-Israeli peace talks from collapse.
One main objective of the US rapprochement towards Damascus, which began after Obama took power last year, is to drive a wedge between Syria's secular ruling hierarchy and Iran's religious Shia rulers, analysts say.
"Syria does not want Lebanon to go haywire and Iran does not want Hezbollah weakened by domestic conflicts as a force against Israel"
The United States also wants Syria to distance itself from Iranian-backed Lebanese Shia group Hezbollah.
A US official said after the Clinton-Moualem meeting that Syria was "very interested" in renewing peace talks with Israel as part of a Middle East settlement pursued by Washington.
But Washington, the official said, was concerned about "Syria's activities inside Lebanon" and its relationship with Hezbollah, which Washington accuses Damascus of arming with the help of Iran in contravention of a United Nations resolution.
Thabet Salem, a Syrian journalist and political commentator, said talks between Syria and Washington will worry Iran less if Iranian-US ties become less hostile.
"The Syrians have made it clear that Damascus' ties with the United States are theirs only to handle," Salem told the Reuters news agency.
While Iran has strongly criticised the US-sponsored peace talks, Syria has kept its objections low key.
Syria has also taken a softer stance towards Mahmoud Abbas, the Palestinian president, in the last several months and is hosting a second round of talks between Hamas and Abbas' Fatah faction this month to try to narrow the divide between the two Palestinian groups.
But Hezbollah remains the lynchpin of Syria's alliance with Iran, having acted as a formidable proxy force in conflicts with Israel - most recently in the 2006 war.
A Damascus-based diplomat said neither Syria nor Iran wants to see Hezbollah compromised by a domestic row over an international tribunal investigating the 2005 assassination of Rafiq al-Hariri, Lebanon's former prime minister.
Hezbollah officials said the tribunal could indict some of the group's members, tainting its credibility, and hinted that an indictment could plunge Lebanon into renewed instability.
"Syria does not want Lebanon to go haywire and Iran does not want Hezbollah weakened by domestic conflicts as a force against Israel," the diplomat said.
Damascus's alliance with Tehran dates to the 1979 Islamic Revolution, when Syria cultivated Iranian-backed clerics in neighbouring Lebanon and was the only Arab country that supported Iran in its 1980-1988 war with Iraq.
Iraq has been the focus of the talks between al-Assad and Ahmadinejad on the two trips the Iranian leader has made to Syria this year. The two leaders are expected to discuss the Iraqi government crisis again during al-Assad's current visit.