Iran's elite Revolutionary Guards launched a drone attack against targets in Israel on Saturday, Iranian English-language press TV cited Iranian sources as saying.

A senior commander in the Corps' Quds force, Mohammad Reza Zahedi, had been killed on April 1 in an airstrike on Iranian diplomatic premises in the Syrian capital, Damascus, that Iran blamed on Israel, prompting Iranian Supreme Leader Ayatollah Ali Khamenei to vow revenge.

Following are some questions and answers about the IRGC, Iran's dominant military force, which has its own army, navy, air force and intelligence wing: 

WHAT IS THE IRGC?

It was set up shortly after the 1979 Islamic Revolution to protect the Shi'ite Muslim clerical ruling system and provide a counterweight to the regular armed forces.

It answers to Supreme Leader Ayatollah Ali Khamenei. The IRGC has an estimated 125,000-strong military with army, navy and air units. It also commands the Basij religious militia, a volunteer paramilitary force loyal to the clerical establishment that is often used to crack down on anti-government protests. 

Basijis mounted "human wave" attacks against Iraqi troops during a war in the 1980s. In peacetime, they enforce Shi'ite Iran's Islamic social codes. Analysts say Basij volunteers may number in the millions, with 1 million active members.

The Quds Force is the IRGC's overseas arm , which heavily influences its allied militias across the Middle East, from Lebanon to Iraq, Yemen and Syria. Its members have fought in support of President Bashar al-Assad in Syria's civil war and have backed Iraqi security forces in their battle against Islamic State militants in recent years.

Its top commander, Major-General Qassem Soleimani, was killed by the United States in a drone attack in Iraq in 2020 that raised fears of a major conflict.

The IRGC, branded a terrorist group by the United States, has sought for years to shape the Middle East according to Iran's interests. In 1982, it founded the heavily armed Shi'ite political movement Hezbollah in Lebanon as a vehicle to export Iran's Islamic Revolution and fight Israeli forces that had invaded Lebanon that year. 

Hezbollah is now a major military force that has played a role in regional conflicts. 

WHAT ARE THE IRGC'S MILITARY CAPABILITIES?

The IRGC oversees Iran's ballistic missile programme, regarded by experts as the largest in the Middle East.

The Guards have used the missiles to strike Sunni Muslim militants in Syria and Iranian Kurdish opposition groups in northern Iraq. The United States, European powers and Saudi Arabia blamed Iran for a 2019 missile and drone attack that crippled the world's biggest oil processing facility in Saudi  Arabia, though Iran denied any involvement. 

Former U.S. president Donald Trump pointed to Iran's missile programme as one of the points not addressed in its 2015 nuclear deal with world powers and cited that as a reason for pulling out of the agreement in 2018. 

The Guards have extensive conventional combat hardware and capabilities, which were showcased in their involvement in the conflicts in Syria and Iraq.

WHAT IS THE IRGC'S POSITION IN IRAN'S POLITICAL SYSTEM?

Former Revolutionary Guards officers occupy key positions in Iran's establishment, from the government to parliament. Most of President Ebrahim Raisi's cabinet are former IRGC officers.

The IRGC's mandate to protect revolutionary values has prompted it to speak out when it felt the system was threatened.

WHAT ABOUT BUSINESS INTERESTS?

After the 1980s war with Iraq, the IRGC became heavily involved in Iran's reconstruction. It has since expanded its economic interests to include a vast network of businesses worth billions of dollars, ranging from construction and telecommunication to oil and gas projects.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)