The international organization's presence in Lebanon include the Office of the UN Special Coordinator for Lebanon (UNSCOL) who serves as the secretary-general's representative to the Lebanese Government, all political parties and the diplomatic community based in the country, and works on behalf of the UN chief to assist Lebanese parties to reach peaceful and consensus based solutions to contentious issues.
The resignation marks the end of a shaky Shia-Sunni political alliance forming the government, which has somewhat managed to keep away the violence battering neighbouring Syria.
In Friedman's view, "Hariri's resignation can be viewed as the opening volley of Saudi Arabia to challenge Hezbollah's dominance in Lebanon".
That's a lot of countries to be at war with. At first blush, that would not seem consistent with King Salman and MBS's overall desire to confront Iran's proxies on every front.
A member of Hezbollah's central committee, Sheikh Nabil Kawouk, accused Riyadh of being behind Hariri's resignation, saying in a speech reported by Lebanon's al-Jadeed television: "God protect Lebanon from the evil of Saudi Arabia's reckless adventures".
But in order to understand the actual dynamics leading to Hariri's resignation, it is necessary to keep in mind how he, backed by Riyadh like his assassinated father, came to be prime minister to begin with only a year ago.
Moreover, having Hariri as prime minister gave legitimacy to Aoun and to Hezbollah even as they held the real power.
"The Saudis felt that Hariri was not delivering and that Hezbollah and Iran were using [the governing arrangement] for their interest", said Shavit. The UNIFIL mandate was extended in September 2017, a step that the UN chief welcomed and expressed confidence that it will have a role in supporting a peaceful political environment in Lebanon.
It is hard to predict how Hariri's resignation will effect Israeli interests. Iran was sowing strife, destruction and ruin wherever it went and accused it of a "deep hatred for the Arab nation", he said.
Mr Hariri has been prime minister since December 2016, after previously holding the position between 2009 and 2011.
Hariri has visited Saudi Arabia twice in the past week, meeting Crown Prince Mohammed and other senior officials. "If the Saudis are right and it limits Hezbollah and Iran, Israel will gain". He has postponed a visit to Kuwait and directed military and security agencies "to maintain stability", it said. The company was hit by a decline in oil prices led to sharp state spending cuts in the kingdom.