KUWAIT CITY -- U.S. Military Forces and Persian Gulf Arab states preparing for war against Iraq have taken steps to protect oil fields, refineries and tankers from an Iraqi counter-attack or a militant bombing, AFP reported.

Analysts, however, doubt that Iraq could hit Persian Gulf targets with missiles or that militants could cripple Persian Gulf shipping with a terrorist campaign.

But they do not rule out a repeat of one-off bombings such as those against the U.S. warship Cole or French oil tanker Limburg.

Industry sources from Japan and other Asian countries which rely on Persian Gulf states for most of their oil also thought the risk of disruption was low.

But one source said Japanese tanker crews may refuse to travel to the Persian Gulf if war breaks out.

An armada of U.S. and allied vessels is available to protect tankers, while the U.S. Coast Guard has brought equipment to contain any oil spill if Iraq repeats the "environmental terrorism" it used in the 1991 Persian Gulf War, a U.S. Navy spokesman said.

Bahrain-based Lieutenant Josh Frey was referring to the setting alight of Kuwait's oil wells as Iraqi forces retreated from the emirate under attack from U.S.-led forces.

"We have assets in the sea and in the air to monitor shipping in the international waters of the Central Command area of responsibility," which includes the Persian Gulf as well as Pakistan and Afghanistan, Frey told AFP when asked how tankers could be protected.

Frey said a total of 90 U.S. and other allied ships -- a fleet that has grown over the years to first enforce UN sanctions on Iraq and then also arrest militants fleeing U.S. troops fighting in Afghanistan -- were available if necessary.

He declined to give details.

Kuwaiti Oil analyst Kamal Al-Harami said he was confident that U.S. and allied naval ships will protect oil tankers in the Persian Gulf and that the thousands of U.S. and British troops deployed in the Kuwaiti desert near Iraq would provide an important buffer for oil fields and refineries.

Kuwait has nonetheless taken its own security measures.

The Kuwaiti Oil CO. said Monday that the Abdali and Riqqa oil fields have been shut down and all others near the border with Iraq will also be closed but the emirate's total production capacity of 2.1 million barrels per day (bpd) will be maintained with fields in the south.

The Defense Ministry declared the north of Kuwait a "military exclusion zone" as of February 15, and restricted entry without a permit from intelligence or security departments.

British analyst Jon Marks said Iraq did not appear for now to present a "credible" missile threat but that Persian Gulf states and allied forces had to look out for militant groups like Al-Qaeda, which are warning of retaliation for any U.S. war on Iraq.

"Western shipping has proven to be a successful target for Al-Qaeda in the past," said Marks, director of Cross Border Information, a British political risk consultancy and publisher. "An actual campaign ... to really cripple Persian Gulf shipping is very unlikely," Marks said. "That doesn't exclude something spectacular from happening."

The risk of terrorism would increase the longer a war lasted and "you'd have to assume more protection" measures, he added.

An Asian industry source in the region who asked not to be named said he had "slight concerns" about both the possibility of an Iraqi missile strike against oil facilities or an act of terror, like the one when an explosives-packed boat hit the French tanker Limburg off Yemen last year. However, he remained optimistic. "In the case of war, the supply of crude will not be seriously affected," he said. "We believe the oil producers in the region will take due measures to maintain stability in the oil market should the said war break out."

Saudi Arabia has already offered to dramatically boost ouptut if war produces a shortage, though Harami questioned how quickly it could do that.

A Japanese oil industry source who asked not to be named said that Japanese tanker crews were threatening through their unions not to travel to the region in the event of a war -- a move that would raise prices by forcing companies to rent vessels on the spot market. "Physically we can deliver the crude oil," he said. "But the cost would increase."