Robert Ford, the first US ambassador to Syria since 2005, arrived Sunday in Damascus where he will have a challenging task to re-engage the two countries which disagree on a raft of important issues.
"The US ambassador arrived in Damascus," a US embassy source said.
"He will not have any official meetings before submitting his credentials to President Bashar al-Assad," in line with protocol, the source said, adding that the procedure should take place within the week.
Ford's arrival comes almost six years after Washington withdrew Ambassador Margaret Scobey, currently US ambassador to Cairo, days after the February 2005 assassination in Beirut of ex-premier Rafiq Hariri in a massive car bomb.
The attack was widely blamed on Syria but Damascus has always denied the allegations.
A career diplomat with wide knowledge of the Arab world, Ford takes up his post at a time of renewed tensions in neighboring Lebanon, where the Syrian- and Iranian-backed Hezbollah and its allies quit the government on Wednesday over a UN-backed probe into Hariri's murder.
The appointment of Ford "shows that President (Barack) Obama wants to work with Syria even if we don't agree on every issue," the US embassy source in Damascus said.
"The ambassador's first priority will be to deliver messages from the American government to the Syrian government," the source added, without elaborating.
The appointment should not be viewed as a "reward" for the Syrian government, State Department spokesman Philip Crowley said on January 7 as Ford was sworn in by Secretary of State Hillary Clinton.
Washington wants Syria to drop its support for the Islamist Hamas movement which controls the Gaza Strip as well as for Hezbollah, and to distance itself from its long-time ally Iran.
The United States has accused Syria and Iran of providing Hezbollah with missiles and sophisticated rockets which can threaten stability in Lebanon as well as the region.
Syria for its part wants the superpower to pressure Israel to pull out of the Golan Heights, which it has occupied since 1967, Syrian analyst Sami Moubayed told AFP.
Washington "is conscious of the necessity to engage a dialogue with Syria," Moubayed said, stressing however that Damascus would not "negotiate" its ties to Hezbollah which he said were solid.
Ford's arrival comes as the prosecutor of the Special Tribunal for Lebanon (STL), based in The Hague, is expected Monday to submit the chargesheet which media reports have said will implicate Hezbollah members in the murder.
Prosecutor Daniel Bellemare will submit his findings to pre-trial judge Daniel Fransen at a hearing behind closed doors, and Hezbollah members will be targeted, French newspaper Le Monde said on Saturday on its Internet site.
The United States is a strong backer of the tribunal and last week Clinton accused Hezbollah and its allies of trying to wreck the UN probe and warned that the move will fail.
"We believe that the work of the special tribunal must go forward, so justice can be served and impunity ended," she said during a visit to Qatar.
"We believe that the leaders of Lebanon have an ongoing responsibility to serve the interests of their own people, not outside forces," she said, apparently referring to Hezbollah allies Iran and Syria.
"Trying to bring the government down as a way to undermine the special tribunal is an abdication of responsibility but it also will not work," Clinton said.
Obama named Ford to the post last February, but because of Republican opposition was not able to confirm the appointment until December 29, when he bypassed Congress while it was not in session.
Ford is a veteran diplomat in the Arab world who has served as ambassador to Algeria and held senior posts in the US embassy in Baghdad.