Iran recently conducted a successful flight test of its Shahab-3 ballistic missile, which is capable of reaching Israel, U.S. officials said.

The test, which took place earlier in May, is believed to be the missile's fifth. Some previous tests have been failures.

"It shows they are continuing to move forward with their missile programs," said one U.S. official, speaking Thursday on the condition of anonymity.

The Shahab-3 has a range of 810 miles, enough to reach Israel and U.S. troops stationed in the region — including Saudi Arabia, Afghanistan, Pakistan and parts of Turkey.

U.S. intelligence officials have said Iran can probably fire a few Shahab-3s in an emergency, but hasn't yet developed a completely reliable weapon. A defense official said Iranian doctrine suggests Iran would probably fire as many missiles as it can in a crisis, expecting only a few to reach their targets.

Iran also fields Scud missiles, which can hit targets about 300 miles away.

The Shahab-3 is based on the North Korean No Dong missile, and Iran receives substantial assistance from North Korea, China and Russia with its missile program. Iran would like to be able to produce its own missiles, according to U.S. intelligence.

Previous Shahab-3 tests are known to have taken place in July 1998, July 2000, and September 2000. "Shahab'' means "meteor'' or "shooting star'' in Farsi.

The United States can monitor such tests from early warning satellites used to look for nuclear missile launches.

Iran's missile programs, as well as its effort to produce chemical, biological and nuclear weapons, are reasons President George W. Bush named Iran as a member of the "axis of evil.'' The United States also says Iran supports terrorist groups like Hezbollah.

Iranian officials have also said they intend to develop missiles called the Shahab-4 and Shahab-5.

The Shahab-4, thought to be in its planning stages, would probably be based on North Korea's Taepo Dong 1 and be able to reach targets in Europe. U.S. officials believe the Shahab-5 is almost purely theoretical, some kind of proposed space launch vehicle that would have applications as an intercontinental ballistic missile capable of reaching North America.

U.S. intelligence has estimated that Iran, if it continues on its present course, will probably have ICBMs capable of reaching the United States in the middle of the next decade.