May 18 (Reuters) - Syrian President Bashar al-Assad's invitation to an Arab Summit in Saudi Arabia on Friday is part of a wider trend in the Middle East where adversaries have been taking steps to mend ties strained by years of conflict and rivalry.
The shift has accelerated since Iran and Saudi Arabia, the region's leading Shi'ite and Sunni Arab powers, agreed to reestablish diplomatic ties in a deal brokered by China in March. Here is how the ententes are playing out:
Although Iran's nuclear programme remains a source of tension, violence between Israelis and Palestinians has been surging, and a new conflict has erupted in Sudan, diplomacy has eased a number of rivalries in the region.
The trend is seen to reflect efforts to boost economic development but also geopolitical shifts as U.S. allies question Washington's long-term commitment to the region despite reassurances from it. It also comes at a time when other powers - notably China - seek more sway.
"The Arabs, the Iranians, and the Turks are trying to create a grey area where they can all coexist, rather than a region of black and white," said Vali Nasr of the Johns Hopkins School of Advanced International Studies in Washington.
Some U.S. allies had concluded their interests are not best served by a highly polarised Middle East, he added. "There is a dynamic in the region that is pushing everyone to the middle."
Saudi Arabia and Iran have agreed to reestablish relations in a deal brokered by China. The agreement could defuse tensions and conflicts including the Yemen war.
The deal underlines Saudi Arabia's desire for security as Crown Prince Mohammed bin Salman focuses on expanding and diversifying the economy. Saudi Arabia has turned to China at a time of strain in its alliance with the United States.
Iran, its economy constrained by U.S. sanctions, is meanwhile seeking to undercut Western efforts to isolate it. China is a big trading partner for both Saudi Arabia and Iran.
The United Arab Emirates, also driven by economic interests that hinge on its reputation as a safe business haven, moved to engage with Tehran in 2019, upgrading diplomatic ties in August. Iran has appointed an ambassador to the UAE for the first time since 2016.
Ties soured between Turkey and Saudi Arabia, Egypt and the United Arab Emirates after the Arab Spring uprisings of 2011, when Turkey backed Islamists who were challenging Arab autocrats for power.
Ankara's ties with Riyadh worsened in 2018 when a Saudi hit squad killed Saudi journalist Jamal Khashoggi at the kingdom's Istanbul consulate. Turkish President Tayyip Erdogan accused the "highest levels" of the Saudi government of giving the orders.
Turkey launched a diplomatic offensive in 2021, resulting in state visits and investment deals at a time of deep crisis for the Turkish economy. Saudi Arabia in March agreed to deposit $5 billion at the Turkish central bank.
Ties are also improving between Egypt and Turkey, which opposed the Egyptian army-led overthrow of President Mohamed Mursi of the Muslim Brotherhood in 2013. In March, Turkey's foreign minister visited Cairo for the first time in a decade.
The better ties have been evident in Libya, where Turkey backs the Tripoli government while Egypt and the UAE support eastern factions. Warmer relations have made it easier for warring Libyan parties to stick with a ceasefire, diplomats say.
Egypt, the UAE, Bahrain and Saudi Arabia severed relations with Qatar in 2017 over accusations of Qatari support for terrorism - a broad allusion to Islamist movements, a charge Doha denied.
Saudi Arabia took the lead in rebuilding ties in 2021, declaring an end to the boycott of Qatar. Riyadh and Cairo have appointed ambassadors, while Abu Dhabi and Manama have yet to do so. All but Bahrain have restored travel and trade links.
Israeli ties with the Arab world broadened significantly in 2020 thanks to the U.S.-brokered "Abraham Accords". The UAE and Bahrain were first to normalise ties, driven by mutual concern over Iran, followed by Morocco.
Sudan and Israel announced in February they had finalised a deal normalising ties, though the fate of the agreement - which was to be signed after the transfer of power from a military to civilian government - has been thrown into doubt by conflict between rival military forces in Khartoum.
Israel has hoped for normalisation with Saudi Arabia too.
But although Riyadh has signalled tacit support for the Abraham Accords, allowing Israeli national carriers to fly in its airspace, it says any normalisation would require progress in the Palestinians' long-stalled quest for statehood.
Separately, Turkey and Israel also last year restored ties that had been strained for more than a decade.
Arab states that once backed anti-Assad rebels have restored ties with Damascus despite objections from Washington.
The UAE took the lead when its foreign minister visited Damascus in 2021. The process accelerated after a deadly earthquake hit Syria in February, prompting an outpouring of Arab support, and further gathered pace after the agreement reestablishing Saudi-Iranian ties.
After the quake, the foreign ministers of Jordan and Egypt, both U.S. allies, visited Damascus for the first time since the war began. The Saudi foreign minister visited in April.
Analysts say motives behind the rapprochement include trying to counter the influence of Iran, which helped Assad regain most of Syria. Arab states also want Assad to combat the production and smuggling of narcotics from Syria around the region.
Turkey, which long supported Syria's rebels, has also reopened contacts with Assad, encouraged by Russia. Assad has rejected any meeting with Erdogan unless the Turkish military withdraws from northern Syria.
Writing by Tom Perry, Editing by Alexandra Hudson, Gerry Doyle and Angus MacSwan
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