The United States began planning a full-scale military campaign against Iran that involves missile strikes, a land invasion and a naval operation to establish control over the Strait of Hormuz even before the March 2003 invasion of Iraq, a former U.S. intelligence analyst disclosed.

William Arkin, who served as the U.S. Army's top intelligence mind on West Berlin in the 1970s and accurately predicted U.S. military operations against Iraq, said the plan is known in military circles as TIRANNT, an acronym for "Theater Iran Near Term."

It includes a scenario for a land invasion of the country led by the U.S. Marine Corps, a detailed analysis of the Iranian missile force and a global strike plan against any Iranian weapons of mass destruction, Arkin wrote in The Washington Post.

Meanwhile, Iran appears convinced it can deter or even win a military confrontation with the United States, with the Islamic regime buoyed by high oil prices, support from militants across the region and American woes in Iraq.

The regime gave fresh signals yesterday that it was in no mood for a compromise over its disputed nuclear programme, with officials openly flouting a UN Security Council demand for a freeze in uranium enrichment by April 28.

U.S. and British planners have already conducted a Caspian Sea war game as part of these preparations, the scholar said.

"According to military sources close to the planning process, this task was given to Army General John Abizaid, now commander of CENTCOM, in 2002," Arkin wrote, referring to the Florida-based U.S. Central Command.

But preparations under TIRANNT began in earnest in May 2003, when modelers and intelligence specialists pulled together the data needed for theater-level warfare analysis for Iran, he said.

This effort has never stopped. The plan has since been updated using information collected in Iraq, the analyst pointed out.

Air Force planners have modeled attacks against existing Iranian air defenses and targets, while Navy planners have evaluated coastal defenses and drawn up scenarios for keeping control of the Strait of Hormuz, the gateway to the oil-rich Gulf.

A follow-on TIRANNT analysis, which began in October 2003, calculated the results of different scenarios for action against Iran to provide options to U.S. commanders, Arkin wrote.

The Marines, meanwhile, have come up with their own document called "Concept of Operations" that explores the possibility of moving forces from ship to shore against a determined enemy without establishing a beachhead first.

"Though the Marine Corps enemy is described only as a deeply religious revolutionary country named Karona, it is, with its Revolutionary Guards, WMD and oil wealth, unmistakably meant to be Iran," Arkin said.

Various scenarios involving Iran's missile force have also been examined in another study, initiated in 2004 and known as BMD-I, which is short for "ballistic missile defense -- Iran", Arkin said.

In June 2004, U.S. Defense Secretary Donald Rumsfeld alerted the U.S. Strategic Command in Omaha, Nebraska, to be prepared to implement CONPLAN 8022, a global strike plan that includes Iran.

"The new task force, sources have told me, mostly worries that if it were called upon to deliver 'prompt' global strikes against certain targets in Iran under some emergency circumstances, the president might have to be told that the only option is a nuclear one," Arkin said.

"But after long debate, the highest levels of the military could not forecast a way in which things would end favorably for the United States," the two experts wrote in Sunday's New York Times.

They warned Iran could retaliate against any U.S. military action by using its terrorist networks "that are far superior to anything Al-Qaeda was ever able to field."