As tensions swell in the Persian Gulf, the United States is pressing its fractious Arab allies to accelerate efforts to establish an integrated missile defense network to counter the threat of Iran's growing ballistic arsenal.

That would add considerable weight to U.S. anti-missile defenses in the region, recently reinforced, in any conflict with the Islamic Republic.

It would also mean, and has already, contracts worth billions of dollars for U.S. defense companies that are increasingly dependent on export orders amid stinging cutbacks in U.S. defense spending.

In recent months, the Pentagon has approved the sale of advanced missile, bomb, radar, electronic warfare and aircraft systems to gulf Arab states that not so long ago it would never have allowed, if only because of Israeli opposition.

These days, the Israelis find themselves sharing a common enemy with Saudi Arabia, which could partly explain the lack of opposition to the current sales.

A case in point is the December 2011 sale of two batteries of Lockheed Martin's Terminal High-Altitude Area Defense anti-missile system to the United Arab Emirates. That $1.86 billion deal was the first foreign sale of THAAD. Lockheed Martin says other Gulf Cooperation Council states, most notably Saudi Arabia, are interested in acquiring THAAD as well.

Others U.S. missile-makers like Boeing, Raytheon and Northrop Grumman are raring to go.

Along with the missile hardware, the gulf monarchies will need state-of-the-art radar systems to detect missile threats, command and control systems to coordinate region-wide operations.

U.S. Defense Secretary Leon Panetta, Secretary of State Hillary Clinton and other senior members of President Barack Obama's administration met key figures from the six-member GCC for talks on the missile shield on the sidelines of last week's U.N. General Assembly.

"It's the United States' goal, to encourage the GCC countries to develop this missile defense architecture because ... to truly protect the region through missile defense it requires a regional approach," a senior U.S. official said.

U.S. sources said that high-value contracts for U.S. systems are expected from some of the member states of the GCC -- Saudi Arabia, the United Arab Emirates, Kuwait, Qatar, Oman and Bahrain. But they gave no details.

Still, that will mark a major turnaround. But Iran's ever-growing missile forces -- Israeli analysts say Tehran has an estimated 300-400 ballistic missiles deployed -- and supposedly ever-improving technology are an obvious spur.

The GCC states have long talked of setting up such a network along the western shore of the gulf to counter the perceived threat from Iran on the other side of the strategic waterway through which flows one-third of the world's seaborne oil trade.

But deep-rooted tribal and dynastic differences between the ruling families in the gulf monarchies have prevented any meaningful progress, or even the pooling of data.

Even now, they're still reluctant to embrace multilateral efforts. They can't even agree where to site the command center for a regional system.

This explains why all the U.S. missile-defense sales are conducted on a bilateral basis with the individual GCC states.

Until recently, only the United Arab Emirates, which has built up formidable air strength in recent years, has shown any real interest in missile defense. It has spent an estimated $12 billion on missile defense since 2008.

The Saudis began moving toward acquiring anti-missile defenses and possibly coordinating with the Emirates and Kuwait on developing an integrated missile shield that could mesh with U.S. assets, mainly naval, in the region after the U.S. invasion of Iraq in 2003.

Riyadh spent $1.7 billion in 2011 on upgrading its Raytheon MIM-104 Patriot units and is now eyeing THAAD.

Kuwait wants to buy 60 Patriot PAC-3 missiles, the most advanced variant, worth up to $4.2 billion.

The toppling of Saddam Hussein, whose military forces had blocked an Iranian to the GCC states in his 1980-88 war with Iraq, and the subsequent emergence of a Shiite-dominated government in Baghdad inclined toward Shiite Iran, alarmed the Gulf Arab states.

The U.S. military withdrawal from Iraq in December 2010, and U.S. abandonment of a key ally, Egyptian President Hosni Mubarak, before he was toppled in February 2011, deepened fears the Americans might eventually leave the gulf states in the lurch.