WASHINGTON -- Iran is prepared to launch attacks using long-range missiles, secret commando units, and terrorist allies planted around the globe in retaliation for any strike on the country's nuclear facilities, according to new US intelligence assessments and military specialists.
US and Israeli officials have not ruled out military action against Iran if diplomacy fails to thwart its nuclear ambitions. Among the options are airstrikes on suspected nuclear installations or covert action to sabotage the Iranian program.
But military and intelligence analysts warn that Iran -- which a recent US intelligence report described as ''more confident and assertive" than it has been since the early days of the 1979 Islamic revolution -- could unleash reprisals across the region, and perhaps even inside the United States, if the hard-line regime came under attack.
''When the Americans or Israelis are thinking about [military force], I hope they will sit down and think about everything the ayatollahs could do to make our lives miserable and what we will do to discourage them," said John Pike, director of the think tank GlobalSecurity.org, referring to Iran's religious leaders.
''There could be a cycle of escalation."
President Bush has said military force should be the last resort in international efforts to deter Iran from acquiring a nuclear bomb. Yet Bush has stated unequivocally that the United States would not tolerate an Iranian nuclear arsenal, which the CIA estimates could be in place in three to 10 years. Iran maintains its nuclear program is solely aimed at producing electricity, not weapons.
Israel, which Iran's new president, Mahmoud Ahmadinejad, has threatened to annihilate, asserts that Tehran is much closer to going nuclear and has been far more direct with its counter-threats.
The Israel Defense Forces, which destroyed Iraq's nuclear reactor in 1981, has said it is perfecting ways to launch a preventative strike against Iranian nuclear sites, including outfitting its Air Force with American-made, bunker-busting munitions.
US intelligence officials have said that Iran, which fought a war with Iraq from 1980-1988 that cost one million lives, still has the most threatening armed forces in the immediate region. Its combined ground forces are estimated at about 800,000 personnel. The CIA has concluded that Iran is steadily enhancing its ability to project its military power, including by threatening international shipping.
But it is Iran's unconventional weapons and tactics -- rather than its conventional military -- that would pose the greatest threat, according to the intelligence officials.
Bush's new intelligence chief, John D. Negroponte, outlining the conclusions reached by a variety of US spy agencies, warned in his first overall annual threat assessment this month to Congress that Iran is capable of sparking a much wider conflict it comes under threat.
A major worry: newly acquired long-range missiles. Obtained with the assistance of North Korea, the Shahab 3 could strike Israel and perhaps even hit the periphery of Europe, according to a recent report by the Pentagon's National Air and Space Intelligence Center.
The missiles could also be tipped with chemical warheads and threaten US military bases in the region.
Iran is believed to have at least 20 launchers that are frequently moved around the country to avoid detection.
''Iran has an extensive missile-development program and has received support from entities in Russia, China, and North Korea," the Pentagon report said, estimating their range to be at least 800 miles.
New missile designs under development could travel 400 miles farther, it said, while Iran purchased at least a dozen X-55 cruise missiles from Ukraine in 2001 that are capable of carrying a nuclear warhead as far as Italy.
Meanwhile, Iranian agents and members of the Revolutionary Guard Corps, widely believed to have a large presence in Iraq, could attempt to foment an uprising by the their fellow Shi'ite majority in Iraq or join insurgents in directly attacking US troops there, Negroponte warned.
He reported that Tehran has ''constrained" itself in Iraq because it is generally satisfied with the political trends in favor of the Shi'ite majority and to avoid giving the United States another excuse to attack Iran. But that could change if Iran were targeted militarily.
A leading Shi'ite cleric in Iraq, Moqtada al-Sadr, whose militia has clashed with US troops and rival Shi'ite groups, vowed in a visit to Tehran last month to defend Iran if it were attacked.
The assessment presented by Negroponte said the Iranian regime already provides ''guidance and training" to militant groups in Iraq and ''has been responsible for at least some of the increasing lethality of anticoalition attacks by providing Shia militants with the capability to build" improvised explosive devices.
Government and private analysts assert that Iran's intelligence apparatus and Revolutionary Guard Corps could cause serious damage to US efforts to pacify Iraq.
''The Iranian ayatollahs may deploy an 'asymmetric' answer and incite a Shi'ite rebellion in Iraq," the respected Russian military publication ''Defense and Security," warned last month, referring to a military strategy that employs such tactics as guerrilla warfare. ''That would be disastrous for the United States."
Iran, believed to be responsible for the bombing of a US Air Force barracks in Saudi Arabia in 1996, also would be expected to enlist its terrorist allies around the world to come to its aid if attacked, US officials and private specialists contend.
''Tehran continues to support a number of terrorist groups, viewing this capability as a critical regime safeguard by deterring US and Israeli attacks, distracting and weakening Israel, and enhancing Iran's regional influence through intimidation," according to Negroponte's assessment to Congress.
Primary among them is Hezbollah, the Lebanese terrorist group that killed 241 US Marines when it bombed a Beirut barracks in 1983.
''Lebanese Hezbollah is Iran's main terrorist ally, which . . . has a worldwide support network and is capable of attacks against US interests if it feels its Iranian patron is threatened," according to the report.
''They have all kinds of people that would like to embrace martyrdom," Pike said of Iran, raising the specter that a terrorist group allied with Iran would be capable of launching attacks inside the United States to avenge a strike against Iran.
Intelligence officials also point out that Iran controls a small island at the mouth the Strait of Hormuz and could use missiles and gunboats to temporarily shut off access to the economically vital Persian Gulf, sparking an oil crisis.
''Military attack is not the solution to this problem," Mohammad Mohaddessin, chairman of the foreign affairs committee of the National Council of Resistance of Iran, the leading dissident group, said in a telephone interview from Paris. ''The regime is absolutely focusing on nonconventional responses. Missiles and terrorist operations are the strong points."