Terrorists armed with weapons of mass destruction pose a "genuine threat" to U.S. security, but there is "too much ambiguity" about who would be in charge if an attack took place, according to the first report of a commission appointed to assess the nation's vulnerability.

The 18-member commission, chaired by Virginia Gov. James S. Gilmore III (R), said terrorists armed with ever-changing technology could strike virtually at will against federal, state and local governments that in too many cases fail to communicate with one another.

"The country's seeming inability to develop and implement a clear, comprehensive and truly integrated national preparedness strategy means that we may still remain fundamentally incapable of responding effectively to a serious terrorist attack," said the report. "A major cultural change is needed in government that will allow the exchange of critical information between . . . authorities about actual and potential threats."

The panel, formed to advise Congress and the administration, is made up of retired senior military officers, medical officials, emergency planners and intelligence experts. The group put the finishing touches on its 67-page report earlier this week and delivered it yesterday to Capitol Hill and the White House. A copy was obtained by The Washington Post.

Citing the 1995 Tokyo nerve gas attack, as well as the deadly bombings in Oklahoma City and at the World Trade Center in New York, the report said terrorists now have weapons ideally suited to killing small or large numbers of people and instilling fear and panic in thousands more.

The commission quoted one former Federal Emergency Management Agency director who said that to kill comparable numbers of people within a square mile, terrorists would need as much as 1,762 pounds of nerve gas, or as little as three ounces of botulinal toxin type A or a quarter-ounce of anthrax spores. The commission repeatedly pointed to problems in the exchange of information between the U.S. government and local and state officials, especially when classified information is involved.

"State and local governments have a stake in national security," said one commission member, who asked not to be identified.

The commission, to some extent, is an outgrowth of frustration at the state and local levels over the the federal government's dealings with their smaller agencies. For instance, commission members said that some of their constituents were annoyed with one federal preparedness plan for the nation's 220 most populous cities, which they complained left many other communities unserved.

But despite the complaints about the lack of coordination, congressional Republicans and Democrats alike have generally applauded FBI Director Louis J. Freeh and other federal officials for leading the fight against terrorism. Legislators have sought to bolster the federal government's expertise in combating weapons of mass destruction and have encouraged federal law enforcement officials to work closely with their local counterparts.

Even the commission's generally critical report conveyed a glimmer of good news: "As serious and potentially catastrophic as a domestic terrorist attack might prove, it is highly unlikely that it could ever completely undermine the national security, much less threaten the survival, of the United States as a nation."