Riyadh: The following are milestones in the complex diplomatic relationship between Saudi Arabia and the United States, as President Barack Obama prepares to visit Riyadh on Friday.

- May 1933: US and Saudi Arabia establish full diplomatic relations. The Californian Arabian Standard Oil Company (later Arab American Company or Aramco) explores for oil in the desert country. Saudi Arabia gains full control of Aramco in 1980.

- February 14, 1945: King Abdul Aziz Bin Saud and US President Franklin D. Roosevelt confirm a deal on the USS Quincy to provide the kingdom’s security in exchange for oil. Roosevelt, however, does not receive Saudi backing for the establishment of a Jewish state in Palestine.

- June 16, 1951: A defence accord covers a permanent US military presence in Saudi Arabia in exchange for arms and training.

- October 16, 1973: The October War sparks an Opec oil embargo against the US that lasts from October 20 until March 19, 1974.

- August 1990: Iraq’s invasion of Kuwait sparks the 1991 Gulf War. US and Saudi Arabia are allies first in Operation Desert Shield, then Operation Desert Storm, launched on January 17, 1991, to evict Iraqi forces. Several hundred thousand US-led troops are deployed across Saudi Arabia, which makes the largest financial contribution to the military operations.

- April 7, 1994: Saudi Arabia revokes the nationality of Osama Bin Laden for terrorist activities. From 1979-1989, he organised logistic support for Afghan fighters with Saudi backing, setting up groups which later formed the core of Al Qaida.

- June 25, 1996: A huge truck bomb kills 19 US soldiers and wounds 386 in the Khobar Towers, near a giant airbase in Dhahran. It is the second attack on US forces in eight months in Saudi Arabia.

- August 27, 2001: Saudi Crown Prince Abdullah Bin Abdul Aziz Al Saud, furious about weak US support for Palestinians, tells President George W. Bush in a letter: “It is time for the United States and Saudi Arabia to look at their separate interests.”

- September 11, 2001: The 9/11 plane attacks on the United States by Al Qaida kill almost 3,000 people. Fifteen of the 19 attackers are Saudi nationals. The US complains of a lack of Saudi cooperation in fighting terrorism. Tensions grow further when the Saudis refuse to assist retaliatory strikes in Afghanistan, and when the US invades Iraq in March 2003. Bush keeps secret until July 2003 a US congressional report on Saudi support for terrorist groups.

- August 27, 2003: US air force moves its Gulf headquarters from Saudi Arabia to Qatar, ending a high-profile military presence. US military advisors remain, and since 2010 the US government has approved more than $86 billion (Dh315.8 billion) in weapons sales to Riyadh.

- March 28, 2007: King Abdullah denounces an “illegitimate foreign occupation” of Iraq and says Arabs will not allow “any foreign force to decide the future of the region,” referring to both the US and Iran. Riyadh’s suspicions are fuelled by Arab Spring uprisings and it sends troops to quell unrest in neighbouring Bahrain.

- October 18, 2013: Saudi Arabia turns down a UN Security Council seat, in an unprecedented move, citing the body’s “double-standards” and failure to act against the Syrian regime.