The cold war between Iran and Saudi Arabia has intensified into a hot and bitter one in recent days, following Saudi's execution of a prominent Shia cleric and the subsequent attack on the Saudi embassy in Tehran.
Later, Saudi Arabia escalated tensions further by severing diplomatic ties with Tehran. In a news conference, the Saudi Minister of Foreign Affairs, Adel al-Jubeir gave Iranian diplomats 48 hours to leave the country. Saudi also banned Iranian citizens from entering the kingdom.
However, though matters only recently reached boiling point, tensions have been heating up over the past year. The conflict began with the regional sectarian proxy war in Yemen. Yemeni rebels, known as Houthis, crossed into Saudi Arabia, where they killed two border guards and seized Saudi territory, including the strategically important Mount al-Doud.
This triggered the largest Saudi military operation since the Iraqi invasion of Kuwait in 1990. Yemen's government, as well as the Arabs, accused Iran of arming the Houthis. Iran heavily criticised Saudi Arabia for their intervention in the Shia insurgency in Yemen.
There was further tension after the Hajj stampede in which more than 400 Iranians were killed. Iran accused the Saudi government of causing the tragedy due to their mismanagement.
I happened to be in Iran when the stampede took place in Saudi Arabia and bodies of the pilgrims were returning to Tehran. There was clear anger and resentment among the Iranians against the Saudi government, where Iran's supreme leader threatened Saudi Arabia with "tough and harsh" retaliation.
Firstly, the Iranians blamed the kingdom for its incompetence in managing the annual ritual of Hajj. Secondly, there was anger as Saudi was delaying in releasing the actual figures of the deceased from Iran. Thirdly, the delay by Saudi to repatriate the bodies back to Iran caused further acrimony.
There were demonstrations in Tehran, Qom and Mashad, with Iranian demonstrators carrying black banners and chanting "death to the Al-Saud family". In the meantime, Iranian President Hassan Rouhani, who was in the United States on his scheduled visit, spoke at the United Nations general assembly and criticised the Saudi government for the incident.
Sharply reacting to this criticism, a Saudi prince, Dr Khalid bin Abdullah bin Fahd bin Farhan Al Saud tweeted that "Under the threat of the enemy Zoroastrians -- to the Kingdom -- it is time to think --seriously -- to ban Iranians from coming to Mecca to preserve the safety of the pilgrims."
It was in this backdrop that the beheading of Shia cleric Sheikh Nimr al-Nimr, who Iran says died fighting against the tyrannical Saudi regime, has incited a religious backlash in Iran, which resulted the Iranians in attacking the Saudi embassy.
Saudi-Iranian animosity dates to the 1979 revolution and Saudi backing for Iraq during the Gulf War with Iran. It worsened after the US invasion of Iraq in 2003 and again during the Arab spring as strategic rivalry took on an explicitly sectarian tone.