The Saudi corner
United States: The U.S. is by far Saudi Arabia's oldest ally. The kingdom was the world's second-largest importer of military equipment between 2012 and 2016, getting most of its weapons from the United States, according to the Stockholm International Peace Research Institute.
Israel: When it comes to Iran's nuclear and regional ambitions, Riyadh is aligned with Israel. Both see Iran as a regional threat.
Egypt: Riyadh backs Egypt's President, Abdel Fattah al-Sisi, who in turn supports the Saudi-led war in Yemen. But Egypt is opposed to war with Iran and Hezbollah.
Jordan: Like Saudi Arabia, it is a Sunni Arab monarchy with deep worries about Iran's regional ambitions. King Abdullah II coined the phrase "Shia crescent" in 2004 – a warning that Iran's influence was poised to extend across Shia populations in the Middle East.
The Iranian corner
Iraq: The U.S.-led invasion of Iraq in 2003 and toppling of Saddam Hussein created an opening for Iran. It holds strong influence over the Shia-dominated government in Baghdad, and Iranian militia were instrumental in crushing the Islamic State in Iraq.
Syria: In Syria, the ties of friendship with Iran go back to the 1980s, when Syria backed Iran in its war with Saddam Hussein. Today, Iran is backing the Assad regime with arms and fighters. Together, with Russian military help, they have defeated Islamic State in Syria.
Yemen: The deposed Yemeni president, Abdrabbuh Mansour Hadi, is central to Riyadh's plan to restore Saudi influence to the south and stop Iran. The Houthi rebels, who belong to a branch of Shia Islam, seized control of the capital and have been the target of a relentless Saudi-led air war. The Saudis claim Iran is backing the Houthis.
Lebanon: In Lebanon, Saudi monarchs have backed the Hariri family. In 2005, prime minister Rafik Hariri was killed in a car blast. The militant group Hezbollah, which was created in Lebanon in the 1980s with Iran's help to drive Israeli troops out of Lebanon, was blamed. Iranian-backed Hezbollah forms part of the current government, which was led by Saudi-backed Prime Minister Saad al-Hariri until he stepped down this month, fearing an Iranian plot to have him assassinated.
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