BAGHDAD (Reuters) - Nearly nine years after the United States threw out Saddam Hussein and dissolved his feared security machine, Iraq's rebuilt military is a long way from matching up with regional powers like Saudi Arabia, Iran and Israel.

With little air defense, marginal control of its borders and a tenuous grip on Sunni insurgents and Shi'ite militias, Iraq may depend on American military help for years to come, even as most U.S. troops leave Iraqi soil by mid-December.

But current external threats are few amid Arab Spring turmoil and the Iran nuclear confrontation, analysts say, which may buy time for Iraq's nascent forces to rebuild and re-arm.

A regional power under Saddam with 700,000 troops and an air force of 40,000 aviators flying French Mirage and Soviet MiG combat jets, the Iraqi military was devastated and then disbanded by U.S. occupation forces in 2003.

The ongoing internal battle against a stubborn insurgency and external defense now falls to a security force the government numbers at about 900,000 largely trained by Americans but not yet fully equipped for the task.

"We are ready. But we need help," said General Hamid al-Maliki, head of the Army Aviation Command, echoing the sentiments of many Iraqi leaders. "Very, very big help."

TESTY NEIGHBOURS

A couple of times a week this past summer, neighboring Iran sent a fast boat into Iraqi Gulf waters, testing its defenses, according to a U.S. military official. Iraqi forces responded well, chasing the intruders away without escalating tensions.

The Navy and Marines, about 4,100 strong, took over responsibility this year for guarding Iraq's 35 square nautical mile slice of the Gulf and offshore oil export terminals that are the nation's economic lifeline.

Iranian maritime incursions aside, threats from the region are limited with Iraq still firmly under the wing of the United States, military officials and analysts agree.

"I don't see any external threat to Iraq, frankly, and that means the Iraqi army has time to develop itself further," said Joost Hiltermann, an analyst with International Crisis Group.

It may be a welcome reprieve. In a region bristling with sophisticated weaponry, post-invasion Iraq is a lightweight.

Its powerful combat jet fleet scattered to other countries or buried in the desert by Saddam, it relies on three Hellfire missile-equipped Cessnas and a few weaponised helicopters.

This year it placed a $3-billion order for 18 U.S. F-16s, but their delivery is years away. General Anwar Ahmed, the air force chief, said another 18 F-16s will be ordered next year.

By comparison, Israel has 417 combat aircraft, mainly F-16s, while Saudi Arabia boasts a fleet of 245 and Iran has 290, according to IHS Jane's defense intelligence.

Iraq made a major purchase of 140 M1A1 Abrams tanks and has a total of 190 battle tanks. But Israel has 2,990, Iran 1,895.

Iraqi officials have said they will be unable to defend their air space before 2020. Washington and Baghdad have no formal defense pact when the current agreement expires on December 31. but the United States says it is committed to a secure Iraq.

"If push comes to shove, I wouldn't expect the U.S. just to stand by. I'm sure they'll get involved," said IHS Jane's analyst Craig Caffrey.

With no air force presence on Iraqi soil, though, U.S. help with any incursion into Iraqi air space would come from a base in the region or a ship in the Gulf, meaning a critical delay.

UNDER CONSTRUCTION

When U.S. civil administrator Paul Bremer dissolved what was left of Saddam's army and several other security bodies in May 2003, he effectively sacked 400,000 people in a single stroke.

Two months later, the U.S. army started recruiting for a new Iraqi army, with a promise of food, housing and medical care and $60 a month.

Today the government says it has hired 650,000 police and 250,000 soldiers. U.S. officials say the numbers are smaller, about 450,000 police, 192,000 soldiers, 5,100 special forces, 6,000 airmen and 4,100 sailors and marines. Exaggerating military strength is common practice in the region.

Iraq sorely lags neighboring Iran (350,000) and Israel (133,000 plus 380,000 reservists) in military manpower but its army is now larger than another major regional power, Saudi Arabia (75,000), according to IHS Jane's. The training of the soldiers and police is a work in progress.

Washington and Baghdad failed to reach agreement to station thousands of military trainers in Iraq. The current plan calls for at least 700 civilian trainers to work with Iraqi forces on defense coordination and skills on F-16s, Abrams and other gear.

"Training pilots and making them ready to use these fighters will take at least 3-4 years," Ahmed said. "A big portion of the training will take place in United States of America and a small part will be in Iraq."

At the Taji military base just north of Baghdad sit some of the light helicopters that make up a good part of Iraq's air defense, deployed mostly against al Qaeda and other militants. Between the Air Force and Army Aviation Command, Iraq had only 158 helicopters and fixed-wing aircraft by late summer.

A delivery of weaponised Bell 407s has been delayed from year-end to April next year.

Despite success ramping up oil production to 2.9 million barrels per day, Iraq's military spending -- $5.7 billion last year, according to the Stockholm International Peace Research Institute -- falls far behind the regional powers.

Saudi Arabia, the world's largest oil producer, spent $42.9 billion last year, Israel $13 billion, according to SIPRI.

Lack of equipment, from aircraft to bullets is a common complaint from soldiers. A defense official said 80 percent of the $4 billion army budget goes to salaries.

The military is struggling to buy ammunition for new Abrams tanks, and last year spent $450 million on parts for 1,000 U.S. armored personnel carriers unsuitable for use in Iraq.

THE REAL INTERNAL THREAT

Iraq remains a major battleground for al Qaeda and its affiliates, who along with rival Shi'ite militias launch scores of bombings and other attacks every month. But U.S. and Iraqi military leaders agree the militants have been badly damaged by years of conflict, and pose no real threat to the government.

More worrying, analysts say, are continuing internal divisions along the potentially explosive faultline of the oil-rich northern city of Kirkuk, disputed by Baghdad and Iraq's semi-autonomous Kurdish region, and within the Iraqi forces.

Americans have been mediating between Kurdish and Iraqi forces since the invasion. Sectarian rivalries thrive within the police and army as Sunnis, Shi'ites and Kurds work uneasily together in a Shi'ite-led nation ruled by Sunnis under Saddam.

"The new leaders don't trust the Sunnis, for example. They see them as former regime elements. Potentially a fifth column," Hiltermann said. "Mistrust is still very much there."

"That shouldn't matter if there is no internal conflict in which these divisions would be laid bare. But if things do start to happen you could well see a breaking apart of the military," he said. "I'm not predicting that now. I would put it as an issue to watch for and worry about."