FACTBOX: The Strait of Hormuz, Iran and the risk to oil

(Reuters) - Five Iranian Revolutionary Guard boats provoked three U.S. Navy ships in the Strait of Hormuz, a major oil shipping route off the Iranian coast, over the weekend, CNN reported on Monday.

Analysts say Iran, OPEC's second largest crude oil producer, could seek to impede traffic through the strategic waterway if the United States resorts to military action against the Islamic Republic over its disputed nuclear program.

U.S. naval chiefs are concerned Iran could resort to mining the strait and the wider Gulf in a major conflict.

The sea channel which shares Iran's coastline at the entrance to the Gulf is the world's most important waterway because of the huge volume of oil exported through it daily.

-- Oil flows through the Strait account for roughly 40 percent of all globally traded oil supply, according to the U.S. Energy Information Administration (EIA). The figure fluctuates with changing OPEC output.

-- In May, the International Energy Agency (IEA) estimated 13.4 million barrels per day (bpd) of crude passing through the narrow channel on tankers, down from 16-17 million bpd before a round of OPEC production cuts.

-- An additional 2 million barrels of oil products, including fuel oil, are exported through the passage daily as well as liquefied natural gas.

-- Exports from the world's largest liquefied natural gas exporter Qatar also pass through the Strait en route to Asia and Europe. 31 million tons a year.

-- Ninety percent of oil exported from Gulf producers is carried on oil tankers through the Strait.

-- Senior political figures in Iran have in the past talked of impeding traffic through the international waterway if threatened.

-- In February 2006 the IEA noted Arab and Iranian press reports about political pressure in Iran for shipping to be blocked if U.N. sanctions are applied in connection with its nuclear program.

-- One of U.S. Central Command's (CENTCOM) key missions in the Gulf is to ensure the free flow of oil and energy supplies.

-- Between 1984 and 1987, a "Tanker War" took place between Iran and Iraq, where each nation fired on each other's oil tankers bound for their respective ports. Foreign-flagged vessels were caught in the crossfire.

-- Shipping in the Gulf dropped by 25 percent because of the exchange, forcing the intervention of the United States to secure the shipping lanes.

-- Iran has admitted to deploying anti-aircraft and anti-ship missiles on Abu Musa, an island strategically located near the Strait's shipping lanes.

-- The EIA predicts oil exports passing through the strait will double to between 30 million and 34 million barrels per day (bpd) by 2020.