The commander of the U.S. Pacific Fleet yesterday said countries are doing more to build ballistic missile-defense systems amid greater awareness of the threat from the long-range projectiles.

Adm. Gary Roughead told a conference of about 700 engineers on Kaua'i that the danger from a "significant weapon" would be removed if the ballistic missile threat were overcome.

"Ballistic missile defense is a growing business as far as the numbers and capability out there," Roughead said in remarks transcribed by the fleet public affairs office. "The North Korean missile development program is something that not only we watch closely, but some of the regional nations out there are involved."

He added that "Japan, in particular, is very mindful and very aware of what threat that poses."

Tokyo's interest in missile defense systems grew after North Korea test-fired a missile over northern Japan in 1998.

Roughead spoke before an annual conference of the Directed Energy Professional Society. The group is mostly made up of engineers who develop the high-energy laser and high-powered microwave technology used to defend against ballistic missiles.

Roughead said missile-defense tests were expensive, but he urged the engineers not to be discouraged when their results were disappointing.

"Some of the best lessons I have ever taken away are not from when I've hit it out of the park but when I screwed something up," Roughead said. "That's when I think we learn a lot, perhaps we even learn more."

Society members gathered on Kaua'i, the site of a major missile defense testing facility, for the first time this year.

The group will meet in Albuquerque, N.M., next year.

At this year's gathering, members announced the results of their development programs and explained new discoveries to the group, said Sam Blankenship, the society's executive director.