[3] The two countries shared a common animosity towards then-Iraqi president Saddam Hussein and coordination against the United States and Israel until the fall of the Assad regime after the 2024 Syrian opposition offensives were completed on December 8th.

Both countries established diplomatic relations on 12 November 1946 when has been accredited Envoy Extraordinary and Plenipotentiary of Iran to Syria with residence in Beirut Mr. Zein-el-Abdine Rahnema.

[14] In 1953, Iranian Prime Minister Mohammad Mossadegh and Syrian President Fawzi Selou signed the Syria-Iran Friendship Treaty, but the agreement soon fell apart after both leaders were overthrown.

Post-Revolution Iran represented an opportunity for Syrian President Hafez al-Assad to find a new counterweight to Israel and Iraq, Syria's regional foes.

[16] As the grip of Alawite echelons in the Syrian Baath party tightened; Assad also pursued a close alliance with the Khomeinist theocracy of Iran during the 1980s.

[18] The Syrian leadership, including the current president Bashar Assad himself, belongs predominantly to the Alawite branch of Shi'a Islam.

During the Iran–Iraq War, Syria sided with non-Arab Iran against Iraq and was isolated by Saudi Arabia and some of the Arab countries, with the exceptions of Libya, Lebanon, Algeria, Sudan and Oman.

Iran's Islamic Revolutionary Guard Corps, with Syrian assistance, established and trained the Hezbollah group to spread Khomeini's ideology and repel the 1982 Israeli invasion of southern Lebanon.

[3] Although Iran was deeply ambivalent about the American-led intervention to remove Saddam Hussein from Kuwait,[22] Syria participated in the coalition of nations to fight Iraq.

Syria became increasingly dependent on Iran for political and military support, as Assad was unable to maintain positive ties with other Arab powers during this time.

[23] On 16 June 2006, the defense ministers of Iran and Syria signed an agreement for military cooperation against what they called the "common threats" presented by Israel and the United States.

[25] Currently, Iran is involved in implementing several industrial projects in Syria, including cement factories, car assembly lines, power plants, and silo construction.

[29] Iranian Sr. Foreign Policy Advisor Ali Akbar Velayati declared, "Iran is not prepared to lose this golden counterweight [to Israel].

"[30] Iran reportedly assisted the Syrian government sending it riot control equipment, intelligence monitoring techniques and oil.

[32] According to the U.S. government, Mohsen Chizari (the Quds Force's third-in-command) visited Syria to train security services to fight against the protestors.

[33] In late June 2011, the Supreme Leader Ali Khamenei, stated in regards to the uprising: "In Syria, the hand of America and Israel is evident;" and in regards to the Syrian government: "Wherever a movement is Islamic, populist, and anti-American, we support it."

[40] In June 2017, Iran launched missiles into Syria, targeting Islamic State fighters in retaliation for Tehran terror attacks, which killed 18 people.

[41][42] According to Reuters reports, Iran has persisted several times that all foreign military forces without legal permission should respect Syria's territorial integrity and vacate the country.

[43] In January 2019, Iranian Vice President Eshaq Jahangiri and Syrian Prime Minister Imad Khamis signed 11 agreements and memoranda of understanding in Damascus, in order to bolster a "long-term strategic economic cooperation".

[45] In September 2022, Israeli defense minister Benny Gantz said Iran is using proxy facilities in Syria to develop advanced missile systems and distribute them to its regional allies.

[49] After rebels captured Damascus on December 8, 2024, the Iranian embassy was ransacked, with posters of Iran's leaders, such as Ayatollah Khamenei, Khomeini (who called Syria: “the golden ring of the resistance chain in the region.”),[52] and figures like Hassan Nasrallah and Qassem Soleimani, torn down and scattered across the floors.

[53] The collapse of the Assad regime, a key ally of the Islamic Republic and a longstanding member of the Iranian-led "Axis of Resistance," has been described as a significant blow to the network and a crucial step toward its disintegration.